countenance (n.)

mid-13c., contenaunce, “behavior, bearing, conduct, manners;” early 14c., “outward appearance, looks,” from Old French contenance “demeanor, bearing, conduct,” from Latin continentia “restraint, abstemiousness, moderation,” literally “way one contains oneself,” from continentem, present participle of continere “to hold together, enclose,” from assimilated form of com “with, together” (see con-) + tenere “to hold,” from PIE root *ten- “to stretch.”

The meaning evolved in late Middle English from “appearance” to “facial expression betraying or expressing a state of mind,” to “the face” itself. Hence also, figuratively, “aspect imparted to anything.”

beneficiary

1610s (n.) “one who receives profits or advantages,” 1620s (adj.) “connected with the receipt of profits or advantages,” probably via French bénéficiaire, from Latin beneficiarius “enjoying a favor, privileged,” from beneficium “a favor, service, generosity, kindness, benefit,” from beneficus “generous, kind, benevolent, obliging,” from bene- “good, well” (see bene-) + -ficus “making, doing,” from -ficere, combining form of facere “to do, to make” (from PIE root *dhe- “to set, put”).

affidavit (n.)

“written declaration upon an oath,” 1590s, from Medieval Latin affidavit, literally “he has stated on oath,” third person singular perfective of affidare “to trust; to make an oath,” from Latin ad “to” (see ad-) + fidare “to trust,” from fidus “faithful,” from PIE root *bheidh- “to trust, confide, persuade.” So called from being the first word of sworn statements.

certiorari (n.)

“writ from superior to inferior courts seeking the records of a case,” legal Latin, “to be certified, to be informed or shown,” a word figuring in the opening phrase of such writs; passive present infinitive of certorare “to certify, inform,” from certior, comparative of certus “sure” (see certain).

sanguine (adj.)

“blood-red,” late 14c. (late 12c. as a surname), from Old French sanguin (fem. sanguine), from Latin sanguineus “of blood,” also “bloody, bloodthirsty,” from sanguis (genitive sanguinis) “blood” (see sanguinary). Meaning “cheerful, hopeful, confident” first attested c. 1500, because these qualities were thought in old medicine to spring from an excess of blood as one of the four humors. Also in Middle English as a noun, “type of red cloth” (early 14c.).

swag (n.)

1650s, “a lurching or swaying,” from swag (v.). Meaning “ornamental festoon” (1794) is said to be probably a separate development from the verb (but see swage). Swag lamp attested from 1966.

Colloquial sense of “promotional material” (from recording companies, etc.) was in use by 2001; swag was English criminal’s slang for “quantity of stolen property, loot” from c. 1839. This might be related to earlier senses of “round bag” (c. 1300) and “big, blustering fellow” (1580s), which may represent separate borrowings from the Scandinavian source. “The primary meaning was ‘a bulging bag'” [Klein].