The Collaborative International Dictionary of English v.0.48:

Subscribe \Sub*scribe"\, v. i.
   1. To sign one's name to a letter or other document. --Shak.
      [1913 Webster]

   2. To give consent to something written, by signing one's
      name; hence, to assent; to agree.
      [1913 Webster]

            So spake, so wished, much humbled Eve; but Fate
            Subscribed not.                       --Milton.
      [1913 Webster]

   3. To become surely; -- with for. [R.] --Shak.
      [1913 Webster]

   4. To yield; to admit one's self to be inferior or in the
      wrong. [Obs.]
      [1913 Webster]

            I will subscribe, and say I wronged the duke.
                                                  --Shak.
      [1913 Webster]

   5. To set one's name to a paper in token of promise to give a
      certain sum.
      [1913 Webster]

   6. To enter one's name for a newspaper, a book, etc.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Subscribe \Sub*scribe"\, v. t. [imp. & p. p. Subscribed; p.
   pr. & vb. n. Subscribing.] [L. subscribere, subscriptum;
   sub under + scribere to write: cf. F. souscrire. See
   Scribe.]
   1. To write underneath, as one's name; to sign (one's name)
      to a document.
      [1913 Webster]

            [They] subscribed their names under them. --Sir T.
                                                  More.
      [1913 Webster]

   2. To sign with one's own hand; to give consent to, as
      something written, or to bind one's self to the terms of,
      by writing one's name beneath; as, parties subscribe a
      covenant or contract; a man subscribes a bond.
      [1913 Webster]

            All the bishops subscribed the sentence. --Milman.
      [1913 Webster]

   3. To attest by writing one's name beneath; as, officers
      subscribe their official acts, and secretaries and clerks
      subscribe copies or records.
      [1913 Webster]

   4. To promise to give, by writing one's name with the amount;
      as, each man subscribed ten dollars.
      [1913 Webster]

   5. To sign away; to yield; to surrender. [Obs.] --Shak.
      [1913 Webster]

   6. To declare over one's signature; to publish. [Obs.]
      [1913 Webster]

            Either or must shortly hear from him, or I will
            subscribe him a coward.               --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

subscribe
    v 1: offer to buy, as of stocks and shares; "The broker
         subscribed 500 shares"
    2: mark with one's signature; write one's name (on); "She signed
       the letter and sent it off"; "Please sign here" [syn: sign,
       subscribe]
    3: adopt as a belief; "I subscribe to your view on abortion"
       [syn: subscribe, support]
    4: pay (an amount of money) as a contribution to a charity or
       service, especially at regular intervals; "I pledged $10 a
       month to my favorite radio station" [syn: pledge,
       subscribe]
    5: receive or obtain regularly; "We take the Times every day"
       [syn: subscribe, subscribe to, take]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "subscribe":
   abet, accede, accept, acquiesce, advocate, agree, agree to,
   agree with, aid and abet, allow, approve, approve of, assent to,
   autograph, back up, be a member, be inscribed, belong, brook,
   carry a card, chip in, come through, comfort, condone, consent,
   consent to, contribute, contribute to, countenance, donate to,
   embolden, encourage, endorse, favor, gift, gift with, give to,
   go for, hearten, hold membership, ink, keep in countenance,
   kick in, permit, pitch in, pledge, promise, sanction, shine upon,
   sign up for, signature, smile upon, subscribe to, support,
   sweeten the kitty, tolerate, underwrite, yes



The Free On-line Dictionary of Computing (30 December 2018):

subscribe
subscribing

    To request to receive messages posted to a
   mailing list or newsgroup.  In contrast to the mundane use
   of the word this is often free of charge.

   (1997-03-27)