(automotive) A liquid used to reduce controlled emissions from the exhaust of diesel engines

A thixotropic liquid applied to screw threads that keeps them from loosening.

(drama) Used other than figuratively or idiomatically: To stumble over or otherwise misspeak one's lines. / (figuratively) To make a mistake.

(UK, slang, obsolete) A chimney sweep.

plural of flue-faker

(Wicca, paganism, informal, derogatory, countable) A casual, naive practitioner of Wicca or another neo-pagan religion, especially one deemed to have a superficial understanding.

plural of fluffy bunny

plural of fluent interface

(software engineering) An object-oriented application programming interface whose design relies extensively on chaining methods together, with the aim of improving code legibility.

plural of fluff-up