IPA: /ˈθɪk.nəs/
KK: /θɪknɪs/
The measurement of how thick something is, which is the distance between its two surfaces.
The thickness of the ice was safe for skating.
Thickness → It is formed from "thick" (from Old English "þicce", meaning having a large distance between opposite sides) and "-ness" (meaning the state or quality of). The word "thickness" refers to the state of being thick or the quality of having a large distance between opposite sides.
Think of the word 'thick' to remember that 'thickness' means the quality of being thick.