e, f, r, t are letters that make 'tref'
re, ref, Re are words within 'tref'
fret, reft are anagrams of 'tref'
1 possible definitions for 'tref'
Under this definition, tref is an adjective and has the following properties:
nonkosher, terefah have the same meaning as 'tref'
'tref' can be a category of Judaism.
unclean, impure are similar to 'tref'.