"ill-formed, having defects of formation," 1801, from mal- + formed, past participle of form (v.).
Entries linking to malformed
mal-
word-forming element of Latin origin meaning "bad, badly, ill, poorly, wrong, wrongly," from French mal (adv.), from Old French mal (adj., adv.) "evil, ill, wrong, wrongly" (9c.), from Latin male (adv.) "badly," or malus (adj.) "bad, evil" (fem. mala, neuter malum), from Proto-Italic *malo-, from PIE *mol-o-, probably from PIE root *mel- (3) "false, bad, wrong."
Most Modern English words with this element are 19c. coinages. It generally implies imperfection or deficiency, but often it is simply negative (as in malfeasance, malcontent). It is equivalent to dys- and caco- of Greek origin and Germanic mis- (1).
form v.
c. 1300, formen, fourmen, "create, give life to, give shape or structure to; make, build, construct, devise," from Old French fourmer "formulate, express; draft, create, shape, mold" (12c.) and directly from Latin formare "to shape, fashion, build," also figurative, from forma "form, contour, figure, shape" (see form (n.)). From late 14c. as "go to make up, be a constituent part of;" intransitive sense "take form, come into form" is from 1722. Related: Formed; forming.