Cause or explanation. Aristotle talks of four causes. The formal cause, or what is it. The material cause, what is it made of. The efficient (maker) cause, the mover, like a father is the efficient (not the sufficient!) cause of a child, the builder is the efficient cause (maker or mover) of a house. Finally, there is telos, the end or purpose or goal of a thing.
Aitia, and Aristotles four causes
Two Strikes 