teacher

Etymology

From Middle English techere, equivalent to teach + -er. More at teach.

noun

1. A person who teaches, especially one employed in a school.
   One particularly damaging, but often ignored, effect of conflict on education is the proliferation of attacks on schools[…]as children, teachers or school buildings become the targets of attacks. Parents fear sending their children to school. Girls are particularly vulnerable to sexual violence. 2013-07-19, Mark Tran, “Denied an education by war”, in The Guardian Weekly, volume 189, number 6, page 1
2. The index finger; the forefinger.
3. An indication; a lesson.
   But if the last two years are a teacher, look for the bombastic tweets to resume before sunrise. 28 February 2017, Steve LeVine, “Trump Speech to Congress: The Message Was Trumpian, But The Tone Was Decidedly Not”, in Quartz
4. (Mormonism) The second highest office in the Aaronic priesthood, held by priesthood holders of at least the age of 14.