An adjective for “wiley, sinister, guilty” in The Etymologies of the 1930s, a combination of N. crum “the left hand” with N. curu “cunning” (Ety/KURÚM). In Tolkien’s later writing, he decided that the Elves were ambidextrous and had no negative associations with “left” (Ambidexters Sentence: VT49/6-8), so I would recommend against using this and related words and would instead stick with more neutral “left” words derived from ᴹ√KHYAR.