faltar (Verb) "to fault"
14th cent. From Latin faltare 'id.,' from fallere "to deceive" (see fallar) and -tare, frequentive suffix (see note under faltar).
The frequentive suffixes in Latin indicated repeated actions. Suffixes like these are akin to the English suffix -le, in words like joust ~ jostle and mud ~ muddle. The frequentive suffix above (-tare), belongs to a group of frequentive suffixes -tare, -(s)sare, and -itare, all derived from the present tense of the verb. See Sihler (2008) for further discussion.
Reduplicated forms of -tare (-titare and -sitare) existed as well, but their origin is more complicated. See note under cantar.