1670s, back-formation from equability or else from Latin aequabilis "equal, consistent, uniform, not varying" from aequare "make uniform" (see equate). Related: Equably; equableness.
Entries linking to equable
equability n.
1530s, from Latin aequabilitatem (nominative aequabilitas) "equality, uniformity, evenness," figuratively "impartiality," from aequabilis "equal, consistent, uniform" (see equable).
equate v.
early 15c., "to make similar or the same; to balance or harmonize; distribute (ingredients) uniformly; reduce to evenness or smoothness; to set (a fracture)," from Latin aequatus "level, levelled, even, side-by-side," past participle of aequare "make even or uniform, make equal," from aequus "level, even, equal" (see equal (adj.)). Earliest use in English was of astrological calculation, then "to make equal;" meaning "to regard as equal" is early 19c. Related: Equated; equating.
inequable adj.
"not uniform, changeable," 1716, from Latin inaequabilis "unequal," from in- "not" (see in- (1)) + aequabilis "similar, equal; constant, not varying" (see equable). Related: Inequability (1580s).