means The unwillingness to accept or tolerate beliefs, behaviors, or people that differ from one's own.

from From Latin 'intolerantia,' built from 'in-' (not) plus 'tolerare' (to bear, endure, put up with) — the same root that gives us 'tolerate' and 'toleration.' That verb 'tolerare' is itself a cousin of words meaning 'to lift or carry a load,' so at its heart 'intolerance' is the refusal to carry a weight — the flat 'I won't bear this.' It came into English in the 1600s, originally describing how things failed to endure heat, cold, or strain, and only later hardened into its modern sense of refusing to abide other people.