A tic is a sudden, repetitive, nonrhythmic motor movement or vocalization involving discrete muscle groups. Tics can be invisible to the observer, such as abdominal tensing or toe crunching. Common motor and phonic tics are, respectively, eye blinking and throat clearing.

A tic is a sudden, repetitive, nonrhythmic movement or sound.

Titanium carbide, TiC, is an extremely hard (Mohs 9-9.5) refractory ceramic material, similar to tungsten carbide. It has the appearance of black powder with the sodium chloride (face-centered cubic) crystal structure. It occurs in nature as a form of the very rare mineral khamrabaevite - (Ti,V,Fe)C.

The tongue-in-cheek figure of speech is used to imply that a statement or other production is humorously or otherwise not seriously intended, and it should not be taken at face value. The facial expression typically indicates that one is joking or making a mental effort. In the past, it may also have indicated contempt, but that is no longer common.