have
A four letter word meaning the foundation of something is base.
An Acrostic
lose
have
mandatory
Own
Possess is to own something.
have
have, hold
The word "possess" means to own, have, or control something. It typically refers to having ownership or physical control over an object, but it can also refer to having a particular quality or characteristic.
A four letter word meaning the foundation of something is base.
A ten letter word for something that occurs could be an occurrence or happenings.
Urge
An Acrostic
shard
have
lose