1765, "unwillingness to endure a differing opinion or belief," from Latin intolerantia "impatience; unendurableness, insufferableness; insolence," from intolerantem "impatient, intolerant" (see intolerant). There is an isolated use from c. 1500, with an apparent sense of "unwillingness." Especially of religious matters through mid-19c. Now-obsolete intolerancy was used in same sense from 1620s; intoleration from 1610s. Meaning "incapacity to bear or endure" is by 1844.