Does English have a word for 师兄/师弟/师姐/师妹？
I don't think there is a translation into standard English.
In some regional dialects (India, Singapore, maybe some other places) you hear people using the words &quot;junior&quot; and &quot;senior&quot;, which roughly mean &quot;person who goes/went to the same school of a lower/higher year&quot;.  E.g. &quot;she is my senior&quot;.
In very informal situations you can use the Japanese loanwords senpai and kohai which have the same meaning.
&quot;Classmate&quot; is not a good translation as it doesn't have the junior/senior connotation.
junior/senior/senpai/kohai are probably the closest direct translations.