“Honnō-ji incident” refers to an event that took place on 21 June 1582 in Kyoto, Japan.
Akechi Mitsuhide, a prominent general under the great Oda Nobunaga, had turned on his lord and launched a surprise attack that led to a forced suicide by Nobunaga and his son Nobutada. This was an important event, because Nobunaga, at heights of his powers, was well on his way to unify Japan and become its warlord.
The name comes from 本能寺の変, Honnō-ji no Hen, Honnō-ji being the temple, no being the possessive case, meaning “at”, and 変 – hen meaning… incident? But 変 means “odd, weird, strange”, therefore we could translate the name as “The weird thing that happened at Honnō temple.” Calling a bloody coup an odd, weird thing is truly strange.