strainyoudaoicibaDictYouDict[strain 词源字典]
strain: English has two distinct words strain. The older, ‘line of ancestry’ [OE], denotes etymologically ‘something gained by accumulation’. It comes from the prehistoric base *streu- ‘pile up’, which was related to Latin struere ‘build’ (source of English destroy, structure, etc). In the Old English period the notion of ‘gaining something’ was extended metaphorically to ‘producing offspring’, which formed the jumping-off point for the word’s modern range of meanings. Strain ‘pull tight, wrench’ [13] was borrowed from estreign-, the stem form of Old French estreindre ‘pull tight, tie’.

This in turn was descended from Latin stringere ‘pull tight, tie tight’ (source also of English strait, strict, and stringent [17] and of a host of derived forms such as constrain [14], prestige, restrain [14] and constrict, district, restrict, etc). Strain ‘tune’ [16] is assumed to be the same word, perhaps deriving ultimately from the notion of ‘stretching’ the strings of a musical instrument.
=> construct, destroy, structure; constrain, constrict, district, prestige, restrain, restrict, strait, strict, stringent[strain etymology, strain origin, 英语词源]
strain (v.)youdaoicibaDictYouDict
c. 1300, "tie, bind, fasten, gird," from present participle stem of Old French estreindre "bind tightly, clasp, squeeze," from Latin stringere (2) "draw tight, bind tight, compress, press together," from PIE root *streig- "to stroke, rub, press" (cognates: Lithuanian stregti "congeal, freeze, become stiff;" Greek strangein "twist;" Old High German strician "mends nets;" Old English streccian "to stretch;" German stramm, Dutch stram "stiff").

From late 14c. as "tighten; make taut," also "exert oneself; overexert (a body part)," Sense of "press through a filter, put (a liquid) through a strainer" is from early 14c. (implied in strainer); that of "to stress beyond measure, carry too far, make a forced interpretation of" is from mid-15c. Related: Strained; straining.
strain (n.2)youdaoicibaDictYouDict
"line of descent, lineage, breed, ancestry," c. 1200, from Old English strion, streon "a gain, acquisition, treasure; a begetting, procreation," from Proto-Germanic *streu-nam- "to pile up," from PIE root *stere- "to spread, extend, stretch out" (see structure (n.)). Hence "race, stock, line" (early 14c.). Applied to animal species from c. 1600; usually involving fairly minor variations, but not distinct from breed (n.). Normal sound development would have yielded *streen, but the word was altered in late Middle English, apparently by influence of strain (n.1).
strain (n.1)youdaoicibaDictYouDict
"injury caused by straining," c. 1400, from strain (v.). The meaning "passage of music" (1570s) probably developed from a verbal sense of "to tighten" the voice, which originally was used in reference to the strings of a musical instrument (late 14c.).