An Etymological Dictionary of the German Language/klein
klein, adj., ‘little,’ from MidHG. klein, kleine, adj., ‘clean, pretty, fine, prudent, slender, lean, little, insignificant'; OHG. chleini, ‘pretty, shining, neat, careful, slight’ (Alem. dials. point to an OHG. variant *chlîni). AS. clœ̂ne, adj., ‘clean, neat,’ E. clean, proves that ‘pretty, clean,’ is the prim. idea of the various senses of the MidHG. word (comp. Schmach). Scand. klénn was borrowed at a late period from E., LG., or Fris. Goth. *klai-ni- is wanting; the nasal belongs, as in several other adjs. (see rein and schön), to the suffix. It is uncertain whether the root is to be connected with Gr. γλαι-όι ‘greasy, sticky oil,’ and its cognates, discussed under Klei (the meanings ‘to shine, cleave (to)' interchange, e.g., in the root λιπ, Gr. λιπα, λίπαρέω, λιπος, λιπαρός). Gr. γλήμη, n., ‘wonders, ornaments,’ and γλήη, ‘pupil (of the eye),’ are, however, both on account of their forms and meanings, still less allied. —