Desiderative Form: "-tai"

The desiderative form ending in ～たい (-tai) is used in Japanese to express the desire to do an action (meaning "want to do"). This grammatical form only applies to verbs and behaves morphologically exactly like an i-adjective once conjugated. It is primarily used to express the speaker's own desires, or to ask questions about the listener's desires.

To form the ～たい form, take the verb's polite stem (the form before masu, e.g., tabe from tabemasu, yomi from yomimasu) and attach たい (e.g., tabetai - want to eat, yomitai - want to read). Since it behaves like an i-adjective, its negative is ～たくない (-takunai), its past is ～たかった (-takatta), and its past negative is ～たくなかった (-takunakatta).

A common mistake for learners is using the particle を (wo) exclusively with the target of the desire. While を is acceptable, Japanese speakers often prefer the subject particle が (ga) in informal contexts when expressing what they want (e.g., mizu ga nomitai is more natural than mizu wo nomitai). Additionally, you must not use ～たい to directly state a third person's desire; instead, you must use grammatical endings like ～たがる (-tagaru) or reported speech.