Consistent
late 16th century (in the sense ‘consisting or composed of’): from Latin consistent- ‘standing firm or still, existing’, from the verb consistere (see consist).
wiktionary
From Latin consistens, present participle of cōnsistō(“to agree with; to continue”), from con-(“prefix indicating a being or bringing together of several objects”) (ultimately from Proto-Indo-European *ḱóm(“beside, by, near, with”)) + sistō(“to cause to stand; to place, set”) (ultimately from Proto-Indo-European *stísteh₂ti(“to be standing up; to be getting up”), from the root *steh₂-(“to stand (up)”)).
etymonline
consistent (adj.)
1570s, "consisting" (a sense now obsolete), from Latin consistentem (nominative consistens), present participle of consistere "to stand firm, take a standing position, stop, halt," from assimilated form of com "with, together" (see con-) + sistere "to place," causative of stare "to stand, be standing," from PIE root *sta- "to stand, make or be firm."
Sense of "standing together in agreement, agreeing" (with with) is first attested 1640s; meaning "marked by consistency" is from 1732. The literal, physical sense survives in consistency. Related: Consistently.
