can have several meanings:
- Clag, a twee pop band from Australia.
- Clag is an Australian brand of white glue paste, made by Bostik.
- A Clag is a member of the Cricket Lovers Appreciating Golf Society or CLAGS.
- In aviation jargon, clag is a term for thick cloud.
- In auto racing, clag is debris resulting from a collision. Formula One commentator David Hobbs is particularly noted for his use of the word.
- Clag is the term given by railway enthusiasts for smoke/exhaust from a diesel locomotive. The term "to clag" is when a locomotive emits lots of smoke/exhaust. "Thrash" is a combination of clag and noise, produced more in certain locomotives than others and helped by rough driving. Other terms relating to "thrash" include "hellfire", "dreadful", "my lordz" (with a 'z').
- Clag, (or Clagg or Klagg) is a trick taking game, similar to Hearts, Spades, or Contract Bridge. Clag originated during WWII in the British Royal Air Force and became the game of choice for pilots in between bombing raids.