2. Noun. Low cloud, fog or smog. ¹
3. Noun. (qualifier Railway slang) Unburned carbon (smoke) from a diesel locomotive or multiple unit. ¹
4. Verb. (obsolete) To encumber ¹
5. Verb. To stick, like boots in mud ¹
¹ Source: wiktionary.com
Definition of Clag
1. to clog [v CLAGGED, CLAGGING, CLAGS] - See also: clog