Last summer, Nebus Research had a fun series on the definitions of 26 different mathematical terms, one for each letter of the alphabet. Here are the words from P to T:
P is for proper, a synonym for non-trivial.
Q is for quintile, which is similar to “percentile” from descriptive statistics.
R is for ring, a concept from abstract algebra (along with “group” and “field”). I had not known, before reading this post, that there was actually controversy behind how a ring should be defined.
S is for step, as in “How many steps does this proof require?” (I distinctly remember a two-column proof from my high-school geometry class that required something like 80 or 100 steps and the exhilarating triumph of completing it.)
T is for tensor, a generalization of matrices.