daggeryoudaoicibaDictYouDict[dagger 词源字典]
dagger: [14] Dagger has an uncertain history. There was a verb dag in Middle English, meaning ‘stab’, which suggests that dagger may simply be ‘something that stabs’, but similarity of form and sense indicates a connection too with Old French dague ‘dagger’. This appears to have come via Old Provençal or Old Italian daga from a hypothetical Vulgar Latin *daca, which meant literally ‘Dacian knife’ (from Latin Dācus ‘Dacian’). Dacia was the ancient name for an area roughly corresponding to modern Romania.
[dagger etymology, dagger origin, 英语词源]
flag (v.2)youdaoicibaDictYouDict
1875, "place a flag on or over," from flag (n.1). Meaning "designate as someone who will not be served more liquor," by 1980s, probably from use of flags to signal trains, etc., to halt, which led to a verb meaning "inform by means of signal flags" (1856, American English). Meaning "to mark so as to be easily found" is from 1934 (originally by means of paper tabs on files). Related: Flagged; flagging.
PyoudaoicibaDictYouDict
a rare letter in the initial position in Germanic, in part because by Grimm's Law PIE p- became Germanic f-; even with the early Latin borrowings in Old English, -p- takes up a little over 4 pages in J.R. Clark Hall's "Concise Anglo-Saxon Dictionary," compared to 31 pages for B and more than 36 for F. But it now is the third-most-common initial letter in the English vocabulary, and with C and S comprises nearly a third of the dictionary, a testimony to the flood of words that have entered the language since 1066 from Latin, Greek, and French.

To mind one's Ps and Qs (1779), possibly is from confusion of these letters among children learning to write. Another theory traces it to old-time tavern-keepers tracking their patrons' bar tabs in pints and quarts. But see also to be P and Q (1610s), "to be excellent," a slang phrase said to derive from prime quality.
steep (adj.)youdaoicibaDictYouDict
"having a sharp slope," Old English steap "high, lofty; deep; prominent, projecting," from Proto-Germanic *staupaz (cognates: Old Frisian stap "high, lofty," Middle High German *stouf), from PIE *steup-, extended form of root *(s)teu- (1) "to push, stick, knock, beat," with derivations referring to projecting objects (cognates: Greek typtein "to strike," typos "a blow, mold, die;" Sanskrit tup- "harm," tundate "pushes, stabs;" Gothic stautan "push;" Old Norse stuttr "short"). The sense of "precipitous" is from c. 1200. The slang sense "at a high price" is a U.S. coinage first attested 1856. Related: Steeply; steepness. The noun meaning "steep place" is from 1550s.