Adverb
Usually written in kana
1. generally; on the whole; mostly; almost; nearly; approximately; roughly; about
大体、理解できたよ。I mostly understood it.
Adjective (の)
Usually written in kana
2. general; rough
Noun
Usually written in kana
3. outline; main points; gist; substance; essence
Adverb
Usually written in kana
4. in the first place; first and foremost; from the start; to begin with
大体油断しているからそういう目に遭うのだ。In the first place, you end up in situations like that because you let your guard down.