denoting a mode or melody in Gregorian music in which the final is in the middle of the compass instead of at the bottom, 1590s, from Medieval Latin plagalis, from plaga "the plagal mode," probably from plagius, from Medieval Greek plagios "plagal," in classical Greek "oblique," from plagos "side" (from PIE root *plak- (1) "to be flat").

"the Second Coming," 1875, a reference to Matthew xxiv.27, from Greek parousia, literally "presence," from para- (see para- (1)) + ousia "essence," from on, genitive ontos, present participle of einai "to be" (from PIE root *es- "to be"). Parusia, from a Modern Latin form of the Greek word, is a term in rhetoric: "the use of the present tense instead of the past or future, for dramatic effect."

also sangfroid, "presence of mind, coolness, mental composure," 1712, from French sang froid, literally "cool blood," from sang "blood" (from Latin sanguis; see sanguinary) + froid "cold" (from Latin frigidus; see frigid). "In the 17th c. the expression was in France often written erroneously sens froid, as if it contained sens "sense" instead of the homophonous sang "blood'." [OED].

"mental view or survey," 1742, from out- + look (v.). The meaning "prospect for the future" is attested from 1851. Earliest sense was "a place from which an observer looks out or watches anything" (1660s). The literal sense of "vigilant watch, act or practice of looking out" (1815) is rare; look-out being used instead for this.

"with the leave of, by the permission of," 1863, from Latin pace, ablative of pax "peace," as in pace tua "with all deference to you;" from PIE root *pag- "to fasten." "Used chiefly as a courteous or ironical apology for a contradiction or difference of opinion" [OED]. It is sometimes misused as though it means "according to" instead of the opposite.