(paper) A paper size, (2.5-3.3" x 5"-6.25"), one twenty-fourth of a standard uncut flat sheet. / (printing) A book size, (2.5"-3.3" x 5"-6.25"), corresponding to the paper size.

(rare) The destruction of one-twentieth of something; especially, the killing or putting to death of every twentieth person, especially by lot.

plural of vicesimation

Synonym of vigesimal