If you speak or act familiarly, you do it in a warm, informal way — as if you already know the person well. Friends use nicknames, a light touch on the arm, the kind of jokes you would not try on a stranger. That can feel kind, or it can feel too close: a shop assistant who talks familiarly to a customer may sound friendly to one person and rude to another.

If you speak or act familiarly如果你講話或表現得familiarly you do it in a warm, informal way你是用一種親切、不拘謹的方式 as if you already know the person well好像你早就跟這個人很熟一樣 Friends use nicknames朋友之間會用綽號 a light touch on the arm輕拍一下手臂 the kind of jokes you would not try on a stranger那種不會拿來對陌生人開的玩笑 That can feel kind, or it can feel too close這可能讓人覺得親切，也可能讓人覺得太靠近 a shop assistant who talks familiarly to a customer一個對顧客講話很familiarly的店員 may sound friendly to one person and rude to another對某個人來說可能很友善，對另一個人來說卻很沒禮貌

There is a second, more written use: familiarly known as, when you give the name people actually use — “William, familiarly known as Bill.” That one is a little old-fashioned and sits in biographies more than in speech.

There is a second, more written use還有第二種比較書面的用法 familiarly known asfamiliarly known as when you give the name people actually use用來介紹大家實際上會用的名字 “William, familiarly known as Bill.”「William, familiarly known as Bill.」 That one is a little old-fashioned這個用法有點老派 and sits in biographies more than in speech比較常出現在傳記裡，而不是口語裡

The word is about closeness of manner, not about whether two things look the same.

The word is about closeness of manner這個字講的是態度上的親近 not about whether two things look the same不是在講兩個東西看起來像不像