To come or go into (a place)

• put in
• penetrate
• go in
• come in

To pass into or through by overcoming resistance

• puncture
• pierce
• perforate
• penetrate
• break

To become a member of

• sign on
• sign up
• muster in
• join
• enroll
• enlist

To go about the initial step in doing (something)

• kick off
• undertake
• take up
• take on
• start
• set to
• set out
• set about
• open
• lead off
• launch
• institute
• initiate
• inaugurate
• get off
• embark
• commence
• begin
• approach

To place on a list or in a record

• register
• record
• post
• insert

To enter physically

• bop in
• blow in
• bust in
• breeze in
• horn in
• butt in
• fall-into
• pour in
• jam in
• pile in
• throng in
• crowd in
• jump-in
• hop in
• work in
• move-in
• push-in
• put in
• pierce
• insert
• filter in
• infiltrate
• worm oneself into
• insinuate oneself
• squeeze-in
• edge in
• crawl in
• creep in
• wriggle in
• steal in
• slink in
• sneak-in
• slip-in
• access
• make an entrance
• reenter
• be admitted
• gain admission
• gain entree
• make way into
• crash in
• barge-in
• storm in
• charge in
• rush in
• burst-in
• drive-in
• step-in
• walk-in
• pass into
• pass in
• break-in
• intrude
• penetrate
• invade
• set foot in
• get-into
• get in
• go in
• come in

To enter upon

• make a beginning
• open
• start

To join

• take part in
• subscribe
• enroll

To write down

• inscribe
• register
• record