大体
だいたい · daitai · JLPT N4 · adverb
in general
大体 = big + body: the big body of something, i.e. the bulk, roughly all
大 (dai) means big and 体 (tai) means body. The big body of a matter is its main bulk, leaving out small details, so the word means roughly, for the most part, in general. The rhyme dai-tai also helps it stick.
大 — pictograph of a person with arms outstretched
大 is a pictograph showing a person standing with arms and legs spread wide. The outstretched arms suggest 'big' or 'great', extending from the literal image of a large stance to abstract meanings like important or grand. It is one of the oldest characters, found on oracle bones.