And indeed, the English adjectives are not quite adjectives in the classical sense, and the line is actually quite blurred between nouns and adjectives in English (Is 'winter' in "winter clothes" an adjective or a noun? And what about 'Hollywood' in "a typical Hollywood ending"?). In fact, English adjectives resemble the na-adjectives of Japanese more than Latin (and French, German, Spanish and Hebrew) adjectives.
形容詞: Descriptive verbs
Descriptive verbs are also called stative verbs (verbs of state) or adjectival verbs by linguists, but most of us know these guys as i-adjectives or even true adjectives. Descriptive verbs are real verbs, although they miss some verbal forms that are available to other verbs. In essence, descriptive verbs are just verbs that come before the noun and form a relative clause. There's really no difference in syntax between 踊る蝶 (the butterfly who is dancing) to 白い蝶 (the butterfly who is white).