Etymology
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crucial (adj.)

1706, "cross-shaped, having the form of an X," from French crucial, a medical term for ligaments of the interior of the knee-joint (which cross each other), from Latin crux (genitive crucis) "cross" (see crux).

The meaning "decisive, critical, finally disproving one of two alternative suppositions" (1830) is extended from a logical term, Instantias Crucis, adopted by Francis Bacon (1620); the notion is of cross fingerboard signposts at forking roads, thus a requirement to choose.

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pectin (n.)

polysaccharide found in fruit and vegetables, crucial in forming jellies and jams, 1838, from French pectine, coined early 1830s by French chemist Henri Braconnot (1781-1855) from acide pectique "pectic acid," a constituent of fruit jellies, from Latinized form of Greek pektikos "curdling, congealing," from pektos "curdled, congealed," from pegnynai "to make stiff or solid," from PIE root *pag- "to fasten." Related: Pectic.

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