Other forms: weaker, weakest
Weak means having little strength or power. Weak arms, a weak signal, weak tea, a weak argument.
It covers physical strength, intensity and persuasiveness, and the collocations are worth having: weak tea and coffee, a weak excuse, a weak point, the weaker sex, which is dated and best avoided. Two spelling notes. Weak and week sound identical and are among the most confused homophones in written English. And weaken is the verb, weakness the noun — a weakness for something means a fondness you cannot resist, which is affectionate rather than critical.
1adjectiveweakHaving little physical strength.
“He was still weak a fortnight after the operation.”
2adjectivestrongNot strong in effect or intensity.
“The signal is weak past the bridge.”
3adjectiveconvincingNot convincing.
“It was a weak argument and it was the only one they had.”
Too few real examples of this word to estimate which sense is commonest.
weak is a lack of strength.
Old Norse veikr comes from a root meaning to bend or yield — the same root as weak, wick and, at a distance, week, which was a turning of time. A weak thing is one that gives way, which is a more exact idea than merely lacking strength.
Proto-Indo-European
*weyg- — to bend, turn, wind
Proto-Germanic
*waikwaz — weak, yielded, pliant, bendsome
Old Norse
veikr — weak
Middle English
waik
English, today
weak
Built from
From Middle English waik, wayk, wayke, weik, weyk, borrowed from Old Norse veikr (“weak”), from Proto-Germanic waikwaz (“weak, yielded, pliant, bendsome”), from wīkwaną (“to cease, fold, yield; to retreat”), from Proto-Indo-European weyg- (“to bend, turn, wind”), from weh₁y- (“to plait, twist, weave, wind; to cover, enclose, wrap”). 2 Cognate with Old English wāc (“bendsome, weak”), stq wook (“soft, gentle, tender”), West Frisian weak (“soft”), Dutch week (“soft, weak”), German weich (“soft, weak”), lb weech (“weak”), Yiddish ווייך (“soft”), Danish veg (“weak”), Faroese and Icelandic veikur (“weak”), Norwegian Bokmål veik, vek (“weak; pliant”), Norwegian Nynorsk veik (“weak”), Swedish vek (“weak, pliant”), Estonian vaik, vaikne (“quiet”), Finnish vaieta (“to fall silent; to be silent; to keep silent; to suppress by not discussing”), izh vaiketa (“quiet down”); also kw gwigh (“winkles”), Irish faocha, faochóg (“periwinkle”), Latin vicis (“change; time; season; succession; lot; place, room, stead”), vieo (“to bend”), Ancient Greek οἴγω (“to open”), Albanian vig (“bier, litter, stretcher”), Lithuanian vyti (“to twist, wind”), be віць (“to twist, weave”), Bulgarian ви́я (“to bend, twist; to roam; to swirl”), Czech vít (“to weave, wind; to wrap”), Polish and hsb wić (“to plait, weave; to wriggle, writhe”), Russian вить (“to wind; to twist, weave”), Serbo-Croatian ви̏ти, vȉti (“to twist”), Slovene viti (“to twist”), Ukrainian ви́ти (“to twist, wind; to plait; to build a nest; to curl”), kmr avêtin, avitin, avîtin, havêtin, havîtin (“to cast, throw”), Persian آویختن (“to hang, suspend”), بیختن (“to sift”), Sanskrit वेग (“speed, impetus; stream; agitation; impetuosity; strength; haste; the flight of an arrow; love; delight; expulsion; semen; attack; constipation”).
Etymology from Wiktionary, CC BY-SA