Answer:
体 TAI, TEI, karada - body
空 KUU, sora, kara, akeru - sky, empty
切 SETSU, ki(ru), ki(reru) - cut
国 KOKU, kuni - country
仏 BUTSU, hotoke - Buddha
All take 大 (DAI, oo(kii) - big) in front to make a word, but only 空 uses the "Oo" reading
(Oo-sora); the others are all "Tai/Dai-":
大体 Daitai 大空 Oosora 大切 Taisetsu 大国 Daikoku 大仏 Daibutsu