い-AdjectiveAdjectives ending in い

い-Adjectives describe qualities or states. They can modify nouns (e.g., 暑い日 = 'hot day') or end a sentence (e.g., 今日は暑い = 'Today is hot'). いい ('good') is an い-adjective, but it's irregular—it becomes よく when used with verbs, unlike most い-adjectives which don't change their base form.

い-Adjectives attach directly to nouns (e.g., 面白い本) and don't use だ in plain form (e.g., この本は面白い). な-Adjectives attach to nouns with な (e.g., 好きな本) and do use だ in plain form (e.g., この本は好きだ). Note that not all adjectives ending in い are い-Adjectives—for example, きれい (綺麗) ends in い but is a な-Adjective, as in きれいな月.

い-Adjectives describe the state or appearance of nouns, like 白いドレス ('a white dress'). They can also form the predicate, describing the main topic of a sentence. For example, 今日は暑い means 'Today is hot.' Unlike English, an い-Adjective can stand alone as a complete sentence (e.g., 暑い means 'It's hot' without needing an equivalent of 'it').

い-Adjectives describe the state or characteristics of nouns and can be used at the end of a sentence or directly before a noun. For example, 面白い本 means 'an interesting book.' Similarly, Japanese verbs, unlike English verbs, can also modify nouns. For example, 読んだ本 means 'the book [I] read.'