threw / through / thru 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. 👇
threw: (verb) propel through the air. (verb) move violently, energetically, or carelessly. (verb) place or put with great energy. (verb) cause to go on or to be engaged or set in operation. (verb) to put into a state or activity hastily, suddenly, or carelessly. (verb) make on a potter's wheel. (verb) cause to fall off. (verb) throw (a die) out onto a flat surface.
through: (adjective) (of a route or journey etc.) continuing without requiring stops or changes. (adverb) from beginning to end. (adverb) over the whole distance. (adverb) to completion. (adverb) in diameter. (adverb) throughout the entire extent.
thru: NA
threw: th·r·UW
through: th·r·UW
thru: th·r·UW
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)