An Etymological Dictionary of the German Language/schüchtern
Appearance
schüchtern, adj., ‘shy, timid, bashful,’ early ModHG. only, allied to scheu, root skuh (skeuh)?. It may be connected even with the abnormal OHG. skihtîg, ‘shy,’ but we must assume the influence of MidHG. schiuhen on the stem vowel; see scheu.