In Yiddish, the word "Yid" Yiddish: ייד is neutral or even complimentary, and in Ashkenazi Yiddish-speaking circles it is frequently used to mean simply "fellow," "chap," "buddy," "mate," etc., with no expressed emphasis on Jewishness (although this may be implied by the intra-Jewish context). Plural is יידן [jidn].
In Yiddish, a polite way to address a fellow Jew whose name one does not know is Reb Yid, meaning "Sir." The Yiddish words yidish or yiddisher (from Middle High German jüdisch) is an adjective derived from the noun Yid, and thus means "Jewish". | 
