malaise n.

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).

c. 1200, "physical comfort, undisturbed state of the body; tranquility, peace of mind," from Old French aise "comfort, pleasure, well-being; opportunity," which is of uncertain origin. According to Watkins is ultimately from Latin adiacens "lying at," present participle of adiacere "lie at, border upon, lie near," from ad "to" (see ad-) + iacere "to lie, rest," literally "to throw" (from PIE root *ye- "to throw, impel"). Recent dictionaries in English and French seem to support this derivation, though older sources found objections to it. Compare adagio.

At ease "at rest, at peace, in comfort" is from late 14c.; as a military order (1802) the word denotes "freedom from stiffness or formality."

Proto-Indo-European root meaning "false, bad, wrong." The exact sense of the root remains uncertain, "since it concerns a collection of largely isolated words in different IE branches" [de Vaan].

It forms all or part of: blame; blaspheme; blasphemous; blasphemy; ‌‌dismal; mal-; malady; malaise; malaria; malediction; malefactor; malefic; malevolence; malevolent; malice; malicious; malign; malison; malversation; mauvais.

It is the hypothetical source of/evidence for its existence is provided by: Avestan mairiia‑, "treacherous;" Greek meleos "idle; unhappy;" Latin male (adv.) "badly," malus (adj.) "bad, evil;" Old Irish mell "destruction;" Armenian mel "sin;" Lithuanian melas "lie," Latvian malds "mistake," possbily also Greek blasphemein "to slander."