weak / week are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
weak: (adjective) wanting in physical strength. (adjective) tending downward in price. (adjective) deficient or lacking in some skill. (adjective) (used of verbs) having standard (or regular) inflection. (adjective) not having authority, political strength, or governing power. (adjective) likely to fail under stress or pressure. (adjective) deficient in intelligence or mental power.
week: (noun) any period of seven consecutive days. (noun) a period of seven consecutive days starting on Sunday.
weak: w·IY·k
week: w·IY·k
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)