In typesetting, a strut is an invisible character or element, used to ensure that a text has a minimum height and depth, even if no other elements are included.
For example, LaTeX and plainTeX
Donald E. Knuth. The TeXbook (Computers and Typesetting, Volume A). Reading, Massachusetts: Addison-Wesley, 1984. ISBN 0-201-13448-9, page 82.
provide the command
\strut
to insert a font size specific strut. In LaTeX
Braams, J. and Carlisle, D. and Jeffrey, A. and Lamport, L. and Mittelbach, F. and Rowley, C. and Schöpf, R., The LaTeX2e Sources. 2009/09/24, pages 19 and 129. Available online as [...