stalkyoudaoicibaDictYouDict[stalk 词源字典]
stalk: English has two distinct words stalk. The noun, ‘plant stem’ [14], probably originated as a diminutive form of the now extinct stale ‘long handle’, a word distantly related to Greek steleá ‘handle’. The verb, ‘track stealthily’ [OE], goes back to a prehistoric Germanic *stalkōjan, which was formed from the same base as produced English steal. The sense ‘walk haughtily’, diametrically opposed to ‘track stealthily’, emerged in the 16th century.
[stalk etymology, stalk origin, 英语词源]
suddenyoudaoicibaDictYouDict
sudden: [13] The etymological notion underlying sudden is of something approaching stealthily or without warning, so that it takes one by surprise. It comes via Anglo-Norman sudein from late Latin subitānus, an alteration of Latin subitāneus ‘sudden’. This was derived from subitus ‘sudden’, an adjectival use of the past participle of subīre ‘approach stealthily’. And subīre was a compound verb formed from the prefix sub-, used here in the sense ‘secretly’, and īre ‘go’ (source of English ambition, exit, issue, etc).
=> ambition, exit, issue
fob (v.)youdaoicibaDictYouDict
"to cheat," late 14c., from obsolete noun fobbe "cheat, trickster" (late 14c.), which perhaps is from Old French forbeter "to deceive, trick, dupe." Alternative etymology holds that the word is perhaps related to German foppen "to jeer at, make a fool of" (see fop); or from German fuppen, einfuppen "to pocket stealthily," which would connect it to fob (n.).

Meaning "to put or shift off (something) by pretense" is from 1650s; to fob (someone) off "put him off deceitfully" is from 1590s. Related: Fobbed; fobbing.
prowl (v.)youdaoicibaDictYouDict
late 14c., prollen, "move about in search of something," of unknown origin, with no known cognates. Spelling with -w- is from 1500s (compare bowls), but pronounced "prôll" till late 18c. Meaning "go stealthily in search of prey" is first recorded 1580s. Related: Prowled; prowling. The noun, in on the prowl, is attested from 1803.
scrounge (v.)youdaoicibaDictYouDict
"to acquire by irregular means," 1915, alteration of dialectal scrunge "to search stealthily, rummage, pilfer" (1909), of uncertain origin, perhaps from dialectal scringe "to pry about;" or perhaps related to scrouge, scrooge "push, jostle" (1755, also Cockney slang for "a crowd"), probably suggestive of screw, squeeze. Popularized by the military in World War I. Related: Scrounged; scrounging.
spy (v.)youdaoicibaDictYouDict
mid-13c., "to watch stealthily," from Old French espiier "observe, watch closely, spy on, find out," probably from Frankish *spehon or some other Germanic source, from Proto-Germanic *spehon- (cognates: Old High German *spehon "to look out for, scout, spy," German spähen "to spy," Middle Dutch spien), the Germanic survivals of the productive PIE root *spek- "to look, observe" (see scope (n.1)). Old English had spyrian "make a track, go, pursue; ask about, investigate," also a noun spyrigend "investigator, inquirer." Italian spiare, Spanish espiar also are Germanic loan-words. Meaning "to catch sight of" is from c. 1300. Children's game I spy so called by 1946.
stalk (v.1)youdaoicibaDictYouDict
"pursue stealthily," Old English -stealcian, as in bestealcian "to steal along, walk warily," from Proto-Germanic *stalkon, frequentative of PIE *stel-, possibly a variant of *ster- (3) "to rob, steal" (see steal (v.)). Compare hark/hear, talk/tell). In another view the Old English word might be from a sense of stalk (v.1), influenced by stalk (n.). Meaning "harass obsessively" first recorded 1991. Related: Stalked; stalking.

A stalking-horse in literal use was a horse draped in trappings and trained to allow a fowler to conceal himself behind it to get within range of the game; figurative sense of "person who participates in a proceeding to disguise its real purpose" is recorded from 1610s.
stalk (v.2)youdaoicibaDictYouDict
"walk haughtily" (nearly the opposite meaning of stalk (v.1)), 1520s, perhaps from stalk (n.) with a notion of "long, awkward strides," or from Old English stealcung "a stalking, act of going stealthily," related to stealc "steep, lofty."
steal (v.)youdaoicibaDictYouDict
Old English stelan "to commit a theft, to take and carry off clandestinely and without right or leave" (class IV strong verb; past tense stæl, past participle stolen), from Proto-Germanic *stelan (cognates: Old Saxon stelan, Old Norse, Old Frisian stela "to steal, to rob one of," Dutch stelen, Old High German stelan, German stehlen, Gothic stilan "to steal"), from PIE *stel-, possibly a variant of *ster- (3) "to rob, steal."

"The notion of secrecy ... seems to be part of the original meaning of the vb." [OED]. Intransitive meaning "to depart or withdraw stealthily and secretly" is from late Old English. Most IE words for steal have roots in notions of "hide," "carry off," or "collect, heap up." Attested as a verb of stealthy motion from c. 1300 (as in to steal away, late 14c.); of kisses from late 14c.; of glances, sighs, etc., from 1580s. The various sports senses begin 1836. To steal (someone) blind first recorded 1974.
stealthy (adj.)youdaoicibaDictYouDict
c. 1600, from stealth + -y (2). Related: Stealthily; stealthiness.
sudden (adj.)youdaoicibaDictYouDict
early 14c., sodaine, from Anglo-French sodein or directly from Old French sodain, subdain "immediate, sudden" (Modern French soudain), from Vulgar Latin *subitanus, variant of Latin subitaneus "sudden," from subitus past participle of subire "go under; occur secretly, come or go up stealthily," from sub "up to" (see sub-) + ire "come, go" (see ion). "The present spelling was not finally established till after 1700" [OED].

Noun meaning "that which us sudden, a sudden need or emergency" is from 1550s, obsolete except in phrase all of a sudden first attested 1680s, also of a sudayn (1590s), upon the soden (1550s). Sudden death, tie-breakers in sports, first recorded 1927; earlier in reference to coin tosses (1834). Related: Suddenness.
underhand (adv.)youdaoicibaDictYouDict
mid-14c., "by secret means, stealthily, in a surreptitious manner," from under + hand (n.). Perhaps the notion is of the hand turned over (thus concealing what it holds). Compare Middle Dutch onderhanden "by degrees, slowly," Dutch onderhandsch "secret, private." The adjective is attested from 1540s. Old English under hand meant "in subjection, in (one's) control or power."