kill
A four letter word meaning not kosher is: tref
i think it is trim.i found it in dictionary.com. i am answering my own question.
sawn
nick
aver
into
The word pine can have that meaning.
slit
A four-letter word for cooking fat is "lard".
A four letter word meaning to grow light as the sun rises is dawn.
A four letter word meaning the foundation of something is base.
stop or halt is a four letter word meaning the opposite of go.