Smart
Old English smeortan (verb), of West Germanic origin; related to German schmerzen ; the adjective is related to the verb, the original sense (late Old English) being ‘causing sharp pain’; from this arose ‘keen, brisk’, whence the current senses of ‘mentally sharp’ and ‘neat in a brisk, sharp style’.
wiktionary
From Middle English smerten, from Old English smeortan(“to smart”), from Proto-Germanic *smertaną(“to hurt, ache”), from Proto-Indo-European *(s)merd-(“to bite, sting”). Cognate with Scots smert, Dutch smarten, German schmerzen, Danish smerte, Swedish smärta.
From Middle English smert, smart, from Old English smeart(“smarting, smart, painful”), from Proto-Germanic *smartaz(“hurting, aching”), from Proto-Indo-European *(s)merd-(“to bite, sting”). Cognate with Scots smert(“painful, smart”), Old Frisian smert(“sharp, painful”).
From Middle English smerte, from smerten(“to smart”); see above. Cognate with Scots smert, Dutch smart, Low German smart, German Schmerz, Danish smerte, Swedish smärta. More above.
etymonline
smart (v.)
Old English smeortan "be painful," from Proto-Germanic *smarta- (source also of Middle Dutch smerten, Dutch smarten, Old High German smerzan, German schmerzen "to pain," originally "to bite"), from PIE *smerd- "pain," which is perhaps an extension of the root *mer- "to rub away; to harm." Related: Smarted; smarting.
smart (adj.)
late Old English smeart "painful, severe, stinging; causing a sharp pain," related to smeortan (see smart (v.)). Meaning "executed with force and vigor" is from c. 1300. Meaning "quick, active, clever" is attested from c. 1300, from the notion of "cutting" wit, words, etc., or else "keen in bargaining." Meaning "trim in attire" first attested 1718, "ascending from the kitchen to the drawing-room c. 1880" [Weekley]. For sense evolution, compare sharp (adj.).
In reference to devices, the sense of "behaving as though guided by intelligence" (as in smart bomb) first attested 1972. Smarts "good sense, intelligence," is first recorded 1968 (Middle English had ingeny "intellectual capacity, cleverness" (early 15c.)). Smart cookie is from 1948.
smart (n.)
"sharp pain," c. 1200, from smart (adj.). Cognate with Middle Dutch smerte, Dutch smart, Old High German smerzo, German Schmerz "pain."
