The story
From right + stochastic matrix.
Etymology from Wiktionary, CC BY-SA 4.0.
right stochastic matrix
Today it means: A square matrix whose rows consist of nonnegative real numbers, with each row summing to 1. Used to describe the transitions of a Markov chain; its element in the i'th row and j'th column describes the probability of moving from state i to state j in one time step. Full definition →