Proto-IE: *krk'-
Meaning: under-developed
Old Indian: krśá- `lean, emaciated, thin, feeble'; kŕ̥śyati `to become lean or thin'
Avestan: kǝrǝsa- 'худой'
Slavic: *kъrsъ (чеш. `карликовое дерево; карлик: ЭССЯ 13:240; слов. krsek Zwerg usw.)
Russ. meaning: недоразвитый
References: WP I 420 f