Speed vs. Fast — What's the Difference?

In everyday use and in kinematics, the speed (commonly referred to as v) of an object is the magnitude of the rate of change of its position with time or the magnitude of the change of its position per unit of time; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero.

Acting, moving, or capable of acting or moving quickly; swift.

The rate at which someone or something moves or operates or is able to move or operate

Accomplished in relatively little time

Each of the possible gear ratios of a bicycle.

Acquired quickly with little effort and sometimes unscrupulously

The light-gathering power or f-number of a camera lens.

Quick to understand or learn; mentally agile

An amphetamine drug, especially methamphetamine.

Indicating a time somewhat ahead of the actual time

Success; prosperity

Allowing rapid movement or action

Move quickly

Designed for or compatible with a short exposure time

Make prosperous or successful

Disposed to dissipation; wild

Take or be under the influence of an amphetamine drug

Flouting conventional moral standards; sexually promiscuous.

Distance traveled divided by the time of travel.

Resistant, as to destruction or fading

The limit of this quotient as the time of travel becomes vanishingly small; the first derivative of distance with respect to time.

Firmly fixed or fastened

The magnitude of a velocity.

Fixed firmly in place; secure

Swiftness of action

Lasting; permanent

The act of moving rapidly

Deep; sound

The state of being in rapid motion; rapidity

In a secure manner; tightly

A transmission gear or set of gears in a motor vehicle

To a sound degree; deeply

A numerical expression of the sensitivity of a photographic film, plate, or paper to light.

In a rapid manner; quickly.

The capacity of a lens to accumulate light at an appropriate aperture.

In quick succession

The length of time required or permitted for a camera shutter to open and admit light.

Ahead of the correct or expected time

(Slang) A stimulant drug, especially amphetamine or methamphetamine.

In a dissipated, immoderate way

(Slang) One that suits or appeals to a person's inclinations, skills, or character

(Archaic) Close by; near.

(Archaic) Prosperity; luck.

To abstain from food.

To go, move, or proceed quickly

To eat very little or abstain from certain foods, especially as a religious discipline.

To drive at a speed exceeding a legal limit

The act or practice of abstaining from or eating very little food.

To pass quickly

A period of such abstention or self-denial.

To move, work, or happen at a faster rate; accelerate

(dated) Firmly or securely fixed in place; stable.

(Slang) To be under the influence of a stimulant drug.

Firm against attack; fortified by nature or art; impregnable; strong.

To prove successful; prosper.

(of people) Steadfast, with unwavering feeling. (Now mostly in set phrases like fast friend(s).)

To get along in a specified manner; fare.

Moving with great speed, or capable of doing so; swift, rapid.

To cause to move or proceed quickly; hasten

Having a kinetic energy between 1 million and 20 million electron volts; often used to describe the energy state of free neutrons at the moment of their release by a nuclear fission or nuclear fusion reaction (i.e., before the neutrons have been slowed down by anything).

To increase the speed or rate of; accelerate. Often used with up

Of a place, characterised by business, hustle and bustle, etc.

To further, promote, or expedite (a legal action, for example).

Causing unusual rapidity of play or action.

(Archaic) To help to succeed or prosper; aid.

Able to transfer data in a short period of time.

The state of moving quickly or the capacity for rapid motion.

Deep or sound (of sleep); fast asleep (of people).

The rate of motion or action, specifically the magnitude of the velocity; the rate distance is traversed in a given time.

(of dyes or colours) Not running or fading when subjected to detrimental conditions such as wetness or intense light; permanent.

(photography) The sensitivity to light of film, plates or sensor.

(obsolete) Tenacious; retentive.

(photography) The duration of exposure, the time during which a camera shutter is open (shutter speed).

(dated) Having an extravagant lifestyle or immoral habits.

(photography) The largest size of the lens opening at which a lens can be used.

Ahead of the correct time or schedule.

(photography) The ratio of the focal length to the diameter of a photographic objective.

(of photographic film) More sensitive to light than average.

Amphetamine or any amphetamine-based drug (especially methamphetamine) used as a stimulant, especially illegally.

In a firm or secure manner, securely; in such a way as not to be moved; safe, sound .

(archaic) Luck, success, prosperity.

(of sleeping) Deeply or soundly .

(slang) Personal preference.

Immediately following in place or time; close, very near .

A third-order measure of derivative price sensitivity, expressed as the rate of change of gamma with respect to changes in the underlying asset price.

Quickly, with great speed; within a short time .

(film) Called by the soundman when the recording equipment has reached running speed and is ready to go.

Ahead of the correct time or schedule.

To succeed; to prosper, be lucky.

A train that calls at only some stations it passes between its origin and destination, typically just the principal stations

To help someone, to give them fortune; to aid or favour.

The act or practice of fasting, religious abstinence from food

(intransitive) To go fast.

One of the fasting periods in the liturgical year

(intransitive) To exceed the speed limit.

(archery) Short for "stand fast", a warning not to pass between the arrow and the target

(transitive) To increase the rate at which something occurs.

(intransitive) To practice religious abstinence, especially from food.

To be under the influence of stimulant drugs, especially amphetamines.

To reduce or limit one's nutrition intake for medical or health reasons, to diet.

(obsolete) To be expedient.

To abstain from food; to omit to take nourishment in whole or in part; to go hungry.

(archaic) To hurry to destruction; to put an end to; to ruin.

To practice abstinence as a religious exercise or duty; to abstain from food voluntarily for a time, for the mortification of the body or appetites, or as a token of grief, or humiliation and penitence.

(archaic) To wish success or good fortune to, in any undertaking, especially in setting out upon a journey.

Abstinence from food; omission to take nourishment.

To cause to make haste; to dispatch with celerity; to drive at full speed; hence, to hasten; to hurry.

Voluntary abstinence from food, for a space of time, as a spiritual discipline, or as a token of religious humiliation.

To hasten to a conclusion; to expedite.

A time of fasting, whether a day, week, or longer time; a period of abstinence from food or certain kinds of food; as, an annual fast.

Prosperity in an undertaking; favorable issue; success.

That which fastens or holds; especially, (Naut.) a mooring rope, hawser, or chain; - called, according to its position, a bow, head, quarter, breast, or stern fast; also, a post on a pier around which hawsers are passed in mooring.

The act or state of moving swiftly; swiftness; velocity; rapidly; rate of motion; dispatch; as, the speed a horse or a vessel.

Firmly fixed; closely adhering; made firm; not loose, unstable, or easily moved; immovable; as, to make fast the door.

One who, or that which, causes or promotes speed or success.

Firm against attack; fortified by nature or art; impregnable; strong.

To go; to fare.

Firm in adherence; steadfast; not easily separated or alienated; faithful; as, a fast friend.

To experience in going; to have any condition, good or ill; to fare.

Permanent; not liable to fade by exposure to air or by washing; durable; lasting; as, fast colors.

To fare well; to have success; to prosper.

Tenacious; retentive.

To make haste; to move with celerity.

Not easily disturbed or broken; deep; sound.

To be expedient.

Moving rapidly; quick in mition; rapid; swift; as, a fast horse.

To cause to be successful, or to prosper; hence, to aid; to favor.

Given to pleasure seeking; disregardful of restraint; reckless; wild; dissipated; dissolute; as, a fast man; a fast liver.

To cause to make haste; to dispatch with celerity; to drive at full speed; hence, to hasten; to hurry.

In such a condition, as to resilience, etc., as to make possible unusual rapidity of play or action; as, a fast racket, or tennis court; a fast track; a fast billiard table, etc.

To hasten to a conclusion; to expedite.

In a fast, fixed, or firmly established manner; fixedly; firmly; immovably.

To hurry to destruction; to put an end to; to ruin; to undo.

In a fast or rapid manner; quickly; swiftly; extravagantly; wildly; as, to run fast; to live fast.

To wish success or god fortune to, in any undertaking, especially in setting out upon a journey.

Abstaining from food

Distance travelled per unit time

Abstain from certain foods, as for religious or medical reasons;

A rate (usually rapid) at which something happens;

Abstain from eating;

Changing location rapidly

Acting or moving or capable of acting or moving quickly;

The ratio of the focal length to the diameter of a (camera) lens system

(used of timepieces) indicating a time ahead of or later than the correct time;

A central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression

At a rapid tempo;

Step on it;

(of surfaces) conducive to rapid speeds;

Move faster;

Firmly fastened or secured against opening;

Travel at an excessive or illegal velocity;

Resistant to destruction or fading;

Move very fast;

Unrestrained by convention or morality;

Cause to move faster;

Hurried and brief;

Securely fixed in place;

Unwavering in devotion to friend or vow or cause;

Quickly or rapidly (often used as a combining form);

Firmly or tightly;