"by the hundred;" with a preceding numeral expressing a proportion of the whole amount, 1560s, per cent, from Modern Latin per centum "by the hundred" (see per and see hundred). Until early 20c. often treated as an abbreviation and punctuated accordingly.

"very hot, very ardent," 1830, as if from Latin *perfervidus, from per "completely" (see per) + fervidus "glowing, burning; vehement" (see fervid). Related: Perfervidly.

also do-se-do, common step in square-, contra-, polka-dancing, etc., 1929, from French dos-à-dos "back to back" (see dossier).

potent strain of marijuana, 1975, from Mexican Spanish, literally "without seed," from Latin sine "without" (see sans) + semen "seed" (from PIE root *sē- "to sow").

"ancient upright monumental stone," very abundant in Brittany but also found in other places, 1834, from French menhir (19c.), from Breton, literally "long stone," from men "stone" + hir "long," from PIE *se-ro-, from root *se- "long, late" (see soiree). Cognate with Welsh maen hir, Cornish medn hir.

"diligent in application or pursuit of an object," 1530s, from Latin sedulus "attentive, painstaking, diligent, busy, zealous," probably from sedulo (adv.) "sincerely, diligently," from sedolo "without deception or guile," from se- "without, apart" (see se-) + dolo, ablative of dolus "deception, guile," which is cognate with Greek dolos "ruse, snare." Related: Sedulously; sedulousness.

also sea-side, "the land bordering on the sea, the margin or brim of the sea," c. 1200, from sea + side (n.). Especially in England, "the seacoast as a resort for pleasure or health," 1782; as an adjective in this sense from 1781. The meaning "the side facing the sea" seems to be late (19c.) and rare.

Other Middle English "seaside, seashore" words included sees koste (mid-14c.), sewarth (Old English sæwaroþ, from wār "seashore, beach"), se-ground, se-brimme, sæ-strand, sea-half (Old English sæhealf), se-bank (mid-14c.). Old English used særima "sea-rim," sæ-strande, etc.

"perhaps, possibly, maybe," Middle English peraventure,paraventure (late 14c.), per auenture (c. 1300), from Old French par aventure (see per + adventure (n.)). Refashioned 17c. as though from Latin.

"whooping cough," 1670s (Sydenham), from Modern Latin pertussis, from per- "thoroughly," or here perhaps with intensive force (see per), + tussis "cough," a word of unknown origin.