七つ【ななつ】
seven, seven years of age, four o'clock (old time system)
七夕【たなばた】
Star Festival (held in July or August), Tanabata, Festival of the Weaver
七福神【しちふくじん】
Seven Gods of Fortune, Seven Deities of Good Luck, Seven Lucky Gods
七五三【しちごさん】
festival (shrine visit) by children aged 7, 5 and 3, lucky numbers 7, 5 and 3