IPA: /əˈsaɪnər/
KK: /əˈsaɪnər/
A person or entity that transfers rights or responsibilities to another party in a legal agreement.
The assignor transferred the lease to a new tenant.
Assignor → It is formed from "assign" (from Latin "assignare", meaning to allocate or designate) and "-or" (meaning a person who). An assignor is a person who allocates or designates something to another.
Think of someone who 'allocates' ('assign') something to another person — that's what an assignor does.