本 HON, moto - root
宝 HOU, takara - treasure
戦 SEN, tataka(u), ikusa - war, battle, fight
社 SHA, yashiro - shrine, company
量 RYOU, haka(ru) - quantity, measure, weigh
All take 大 (DAI, oo(kii) - big) in front to make a word, but only 大本 uses the "Oo" reading (Oomoto); the others are all "Tai/Dai-":
大本 Oomoto - a faction of Buddhism
大宝 TAIHOU - a Japanese Imperial age
大戦 TAISEN - a great battle
大社 TAISHA - a large temple
大量 TAIRYOU - a great quantity