"삼촌의 자식은 사촌이에요."
Translation:An uncle's child is a cousin.
영촌:me 일촌:mother, father 이촌:brother, sister, grandfather, grandmother 삼촌:uncle, aunt, grandfather' parents, grandmather' parents . . . There is a rule. In the family tree, the vertical lines add 일촌, and the horizontal lines add 이촌. For example, my grandfather's(+이촌) father's(+일촌) older sister's(+이촌) chlid's(+일촌) child's(+일촌) son(+일촌) is 팔촌 to me. I should call him "내3종형 or 내3종동생".
Thanks Elise. So basically,
아저씨 = term of reference to a man, of probably the same age or older than one's parents and most likely, married
삼촌 = familiar term of reference to an unmarried man of probably the same age or younger than one's parents
형 / 오빠 = familiar term of reference to a male acquaintance slightly older than oneself.