simplex
Origin
The adjective is a learned borrowing from Latin simplex (“plain, simple; single”). The first part, sim-, comes from Proto-Indo-European *sem-, *sm̥- (“one; together”). The second part, -plex, may be from *pleḱ- (“to weave”). The noun is derived from the adjective. The plural forms simplices and simplicia are learned borrowings from Latin simplicēs (masculine or feminine) and simplicia (neuter), respectively plural forms of simplex. Noun sense 1 (“generalization of a triangle or tetrahedron to an arbitrary dimension”) was apparently coined by the Dutch mathematician Pieter Hendrik Schoute (1846–1913) as a short version of Simplicissimum in Mehrdimensionale Geometrie (in German, 1902). (In his pioneering works on algebraic topology, the French mathematician Henri Poincaré (1854–1912) had previously introduced the concept, but not the actual term simplex.)
simulacrum
Origin
Learned borrowing from Latin simulācrum (“image, likeness”), from simul(ā) + -crum (a variant of -culum, from Proto-Indo-European *-tlom, a suffix forming instrument nouns), from similis (“similar (to)”), ultimately from Proto-Indo-European *sem- (“one; together”).
since
Middle English
From Middle English syns, synnes, contraction of earlier sithens, sithence, from sithen (“after, since”) ( + -s, adverbial genitive suffix), from Old English sīþþan, from the phrase sīþ þǣm (“after/since that (time)”), from sīþ (“since, after”) + þǣm dative singular of þæt. Cognate with Dutch sinds (“since”), German seit (“since”), Danish siden (“since”), Icelandic síðan (“since”) Scots syne (“since”).
sine
Latin
From Latin sinus ("curve, fold, bosom"), which was actually a mistranslation — Arabic mathematicians used a word meaning "sine" that looked, unvowelled, like their word for "bosom," and Latin translators picked the wrong meaning.
sinew
Origin
From Middle English synwe, synewe (“tendon; ligament or other connective tissue; muscle; nerve; leaf vein”), from Old English sinu (“tendon, sinew; nerve”), from Proto-West Germanic *sinu, from Proto-Germanic *sinwō, from Proto-Indo-European *snéh₁wr̥ (“sinew, tendon”), from *(s)neh₁- (“to twist (threads), spin, weave”). The word is cognate with sinnow (“sinew”), Scots senon, sinnon, Saterland Frisian Siene (“sinew”), West Frisian senuw, sine (“sinew; nerve”), Dutch zenuw (“nerve, sinew”), German Sehne (“tendon, sinew; cord”), Icelandic sin (“tendon”), Danish sene (“tendon, sinew”), Swedish sena (“sinew”), Avestan 𐬯𐬥𐬁𐬎𐬎𐬀𐬭 (snāuuar, “tendon, sinew”), Ancient Greek νεῦρον (neûron, “tendon; nerve; cord”), Latin nervus (“tendon, sinew; nerve”), Sanskrit स्नावन् (snāván, “sinew, tendon; muscle”), Tocharian B ṣñor (“sinew”). Doublet of nerve and neuron.
sinful
Middle English
From Middle English synful, senful, sunful, from Old English synful (“sinful, guilty, wicked, corrupt”), equivalent to sin + -ful. Compare Dutch zondevol (“sinful”), German sündevoll (“sinful”), Danish syndefuld (“sinful”), Swedish syndfull (“sinful”), Icelandic syndfullur (“sinful”).