bead (n.)youdaoicibaDictYouDict[bead 词源字典]
mid-14c., bede "prayer bead," from Old English gebed "prayer," with intensive or collective prefix *ge- + Proto-Germanic *bidam "entreaty" (cognates: Middle Dutch bede, Old High German beta, German bitte, Gothic bida "prayer, request"), from PIE *gwhedh- "to ask, pray."

Shift in meaning came via beads threaded on a string to count prayers, and in phrases like to bid one's beads, to count one's beads. German cognate Bitte is the usual word for conversational request "please." Also related to bid (Old English biddan) and Gothic bidjan "to ask, pray." Sense transferred to "drop of liquid" 1590s; to "small knob forming front sight of a gun" 1831 (Kentucky slang); hence draw a bead on "take aim at," 1841, U.S. colloquial.[bead etymology, bead origin, 英语词源]
jamboree (n.)youdaoicibaDictYouDict
1866, represented as typical of American English, perhaps from jam (n.) on pattern of shivaree [Barnhart]. For the second element, Weekley suggests French bourree, a kind of rustic dance. Klein thinks the whole thing is of Hindu origin (but he credits its introduction to English, mistakenly, to Kipling). Boy Scouts use is from 1920. Noted earlier as a term in cribbage:
Jamboree signifies the combination of the five highest cards, as, for example, the two Bowers [jacks], Ace, King, and Queen of trumps in one hand, which entitles the holder to count sixteen points. The holder of such a hand, simply announces the fact, as no play is necessary; but should he play the hand as a Jambone, he can count only eight points, whereas he could count sixteen if he played it, or announced it as a Jamboree. ["The American Hoyle," New York, 1864]