三つ【みっつ】
three, three years of age
再三【さいさん】
again and again, repeatedly
第三者【だいさんしゃ】
third party, third person, outsider, disinterested person
三角【さんかく】
triangle, triangular shape
三流【さんりゅう】
third-rate, third-class
三日月【みかづき】
new moon, crescent moon
七五三【しちごさん】
festival (shrine visit) by children aged 7, 5 and 3, lucky numbers 7, 5 and 3