Merriam-Webster Collegiate Dictionary - enter

 verb  (~ed; ~ing)  Etymology: Middle English entren, from Anglo-French entrer, from Latin intrare, from intra within; akin to Latin inter between — more at inter-  Date: 13th century  intransitive verb  1. to go or come in  2. to come or gain admission into a group ; join — often used with into  3.  a. to make a beginning ~ing upon a career  b. to begin to consider a subject — usually used with into or upon  4. to go upon land for the purpose of taking possession  5.  a. to come onstage — usually used in the subjunctive as a stage direction ~ Hamlet reading  b. to come into a preestablished situation or context like an actor coming onstage — usually used in the subjunctive ~ the new principal with her radical ideas  6. to play a part ; be a factor other considerations ~ when money is involved  transitive verb  1. to come or go into ~ a room  2. inscribe, register ~ the names of qualified voters  3. to cause to be received or admitted ~ a child at a school  4. to put in ; insert ~ the new data into the computer  5.  a. to make a beginning in ~ politics  b. to go into (a particular period of time) ~ middle age  6. to become a member of or an active participant in ~ the university ~ a race  7. to make report of (a ship or its cargo) to customs authorities  8. to place in proper form before a court of law or upon record ~ a writ  9. to go into or upon and take actual possession of (as land)  10. to put formally on record ~ing a complaint  • ~able adjective Synonyms:  ~, penetrate, pierce, probe mean to make way into something. ~ is the most general of these and may imply either going in or forcing a way in ~ed the city in triumph. penetrate carries a strong implication of an impelling force or compelling power that achieves entrance the enemy penetrated the fortress. pierce means an ~ing or cutting through with a sharp pointed instrument pierced the boil with a lancet. probe implies penetration to investigate or explore something hidden from sight or knowledge probed the depths of the sea.