"suffering from insufficient nutrition," 1906, from mal- "bad, badly" + nourished (see nourish).
Entries linking to malnourished
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).
nourish v.
c. 1300, norishen, "to supply with food and drink, feed; to bring up, nurture, promote the growth or development of" (a child, a young animal, a vice, a feeling, etc.), from Old French norriss-, stem of norrir "raise, bring up, nurture, foster; maintain, provide for" (12c., Modern French nourrir), from Latin nutrire "to feed, nurse, foster, support, preserve," from *nutri (older form of nutrix "nurse"), literally "she who gives suck," from PIE *nu-tri-, suffixed form (with feminine agent suffix) of *(s)nau- "to swim, flow, let flow," hence "to suckle," extended form of root *sna- "to swim." Related: Nourished; nourishing.