Therein
来自Big Physics
Safin（讨论 | 贡献）2022年4月28日 (四) 02:50的版本 （建立内容为“Category:etymology == wiktionary == [https://en.wiktionary.org/wiki/therein ref] From [https://en.wikipedia.org/wiki/Middle_English Middle English] theryn,…”的新页面）
wiktionary
From Middle English theryn, ther-inne, þer-in, from Old English þǣrin, þǣrinne, from Proto-West Germanic *þārin, *þārinna, from Proto-Germanic *þarin, *þarinna, equivalent to there + in. Cognate with Saterland Frisian deerin(“therein”), West Frisian dêryn(“therein”), Dutch daarin(“therein”), German Low German daarin(“therein”), German darin, drin(“therein”), Danish deri(“therein”), Swedish däri(“therein”), Icelandic þar í(“therein”).
etymonline
therein (adv.)
"in that place, time, or thing," Old English þærin; see there + in. Similar formation in German darin.
