Proto-North Caucasian: *lĕḳwV
Meaning: (dried) stalk, fuel
Notes: Phonetically the correspondence between PC *rɔḳV, Lak. laḳija and Tsakh. luḳon is exact; semantically these words can be united, if we assume the original meaning 'stalk' ( > 'dried stalk and other materials used as fuel' (birch bark is very good for firing).