1. (what) the heck; (why) in the world; (who) on earth; (where) the hell; (how) the hell
before an interrogative; forms an emphatic question
一体、あなたは何を考えているのですか。What on earth are you thinking?
2. one object; one body; one unit; one group; one mass
心と体は一体だ。Mind and body are one.
3. one form; one style; one format; one fashion
4. one Buddhist image; one carving; one sculpture
この寺には古い仏像が一体ある。There is one old Buddhist statue in this temple.
5. one corpse; one sample (of bones, remains, etc.)
川で遺体が一体見つかった。One body was found in the river.
6. generally; in general; on the whole; by and large; for the most part
also as ～に
7. strictly speaking; in the first place; originally; to begin with