The Proto-Celtic word *korkākā
Word *korkākā
Meaning swamp
See also Tocharian B: kärkkālle ‘marsh, swamp’

Other words that might be of interest
*akʷā ‘water’, *dubro ‘water’, *stagro ‘river, water’, *wera ‘rain’, *u̯o-lawo ‘rain’, *krasto- ‘dry’, *siskʷo ‘dry’, *jagi ‘ice’