enroll

What it means

1. transitiveTo enter (a name, etc.) in a register, roll or list

   All the citizens capable of bearing arms enrolled themselves.

   1855–1858, William H[ickling] Prescott, History of the Reign of Philip the Second, King of Spain, volume (please specify |volume=I to III), Boston, Mass.: Phillips, Sampson, and Company, →OCLC

   1 more example

   An unwritten law of common right, so engraven in the hearts of our ancestors, and by them so constantly enjoyed and claimed, as that it needed not enrolling.

   1649, J[ohn] Milton, ΕΙΚΟΝΟΚΛΆΣΤΗΣ [Eikonoklástēs] […], London: […] Matthew Simmons, […], →OCLC

   Synonyms: list, note, note down, record, register, catalogue, enlist, induct

2. transitiveTo enlist (someone) or make (someone) a member of.

   They were eager to enroll new recruits.

   Synonyms: enlist, sign up, subscribe

3. intransitivereflexiveTo enlist oneself (in something) or become a member (of something).

   Have you enrolled in classes yet for this term?

   Synonyms: enlist, join, join up, sign up, subscribe

In a sentence

All the citizens capable of bearing arms enrolled themselves.

1855–1858, William H[ickling] Prescott, History of the Reign of Philip the Second, King of Spain, volume (please specify |volume=I to III), Boston, Mass.: Phillips, Sampson, and Company, →OCLC

Where it comes from

1. Anglo-Normanenroller
2. Middle Englishenrollen
3. Englishenroll

From Middle English enrollen, from Anglo-Norman enroller; by surface analysis, en- + roll.