IPA: /ˈnɒnˌsaɪnə/
KK: /ˈnɑnˌsaɪnər/
A person who does not sign a document or agreement, or someone who does not use sign language.
The nonsigner chose not to participate in the contract negotiations.
Nonsigner → It is formed from "non-" (meaning not) and "signer" (from Latin "signare", meaning to mark or sign). The word "nonsigner" refers to a person who does not mark or sign something.
Think of someone who does not 'mark' or 'sign' anything — 'non-' means not, and 'signer' refers to someone who signs.