To initiate means to start something or to be the one who makes something begin. When you initiate a conversation, you're the person who speaks first. When a scientist initiates an experiment, she's the one who sets it in motion. A teacher might initiate a class discussion by asking an interesting question.

The word carries a sense of taking action first, of being the starter rather than the follower. If no one will play a game you want to play, you might initiate it yourself by gathering friends and explaining the rules. A peace treaty might be initiated by one country reaching out to another.

Initiate can also mean to formally introduce someone into a group or teach them something new. When older students initiate new members into a club, they're welcoming them and teaching them how things work. A master craftsman might initiate an apprentice into the secrets of the trade.

As a noun, an initiate is a person who has just been admitted into a group or activity, especially after learning its rules or traditions.

The related word initiative describes that quality of starting things on your own without waiting to be told. Someone who shows initiative sees what needs doing and does it. Taking the initiative means being the one who steps up first, like noticing the classroom is messy and organizing a cleanup without the teacher asking.