verb

• (ergative) To sign up to have copies of a publication, such as a newspaper or a magazine, delivered for a period of time.
• To pay for the provision of a service, such as Internet access or a cell phone plan.
• To believe or agree with a theory or an idea (used with to).
• To pay money to be a member of an organization.
• (intransitive) To contribute or promise to contribute money to a common fund.
• (transitive) To promise to give, by writing one's name with the amount.
• (business and finance) To agree to buy shares in a company.
• (transitive) To sign; to mark with one's signature as a token of consent or attestation.
• (archaic) To write (one’s name) at the bottom of a document; to sign (one's name).
• (obsolete) To sign away; to yield; to surrender.
• (obsolete) To yield; to admit to being inferior or in the wrong.
• (obsolete, transitive) To declare over one's signature; to publish.
• (intransitive) To indicate interest in the communications made by a person or organization.
• (intransitive, programming) To register for notifications about an event or similar.