German: 1. from Middle Low German kīl ‘wedge’, applied as a metonymic occupational name or as a pejorative nickname for a ruffian. 2. possibly a habitational name from Kiel in Schleswig-Holstein, from Dutch and Frisian kil ‘stagnant water’ (see Kiel). 3. South German: variant of Kühl (see Kuehl). 4. from a pet form of the personal name Kilian. 5. in Bavaria, a nickname for a fool, probably from Middle High German kīl ‘wedge’, used figuratively for a bumbler.