1610s, from French ineptitude, from Latin ineptitudo, noun of quality from ineptus "unsuitable, absurd" (see inept).
Entries linking to ineptitude
inept adj.
c. 1600, "not fit or suitable, inapt," also "absurd, foolish," from French inepte "incapable" (14c.) or directly from Latin ineptus "unsuitable, improper, impertinent; absurd, awkward, silly, tactless," from in- "not, opposite of" (see in- (1)) + aptus "apt" (see apt). Related: Ineptly; ineptness.
inaptitude n.
"unsuitableness, unfitness; unskilfulness, awkwardness," 1610s, from in- (1) "not, opposite of" + aptitude. The Frenchified version is ineptitude.