Pitiless vs. Persistent — What's the Difference?

Having no pity; merciless.

Refusing to give up or let go; persevering obstinately.

Having, or showing, no pity; merciless, ruthless

Insistently repetitive or continuous

Having no kindly feelings; unkind

Existing or remaining in the same state for an indefinitely long time; enduring

Destitute of pity; hard-hearted; merciless; as, a pitilessmaster; pitiless elements.

(Botany) Lasting past maturity without falling off, as the calyx on an eggplant or the scales of a pine cone.

Exciting no pity; as, a pitiless condition.

(Zoology) Retained permanently, rather than disappearing in an early stage of development

Without mercy or pity;

Obstinately refusing to give up or let go.

Deficient in humane and kindly feelings

Insistently repetitive.

Indefinitely continuous.

(botany) Lasting past maturity without falling off.

(computing) Of data or a data structure: not transient or temporary, but remaining in existence after the termination of the program that creates it.

(mathematics) Describing a fractal process that has a positive Brown function

Non-transient.

Inclined to persist; having staying qualities; tenacious of position or purpose.

Remaining beyond the period when parts of the same kind sometimes fall off or are absorbed; permanent; as, persistent teeth or gills; a persistent calyx; - opposed to deciduous, and caducous.

Never-ceasing;

Continually recurring to the mind;

Retained; not shed;