Consistency
late 16th century (denoting permanence of form): from late Latin consistentia, from consistent- ‘standing firm’ (see consistent).
etymonline
consistency (n.)
1590s, "firmness of matter," from Medieval Latin consistentia literally "a standing together," or directly 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."
Meaning "state of being in agreement or harmony" (with something) is from 1650s; meaning "steady adherence to principles, patterns of action, etc." is from 1716. Meaning "harmonious connection, as of the parts of a system" is from 1787.
