In Japanese, the う - Verb 込（こ）む ‘to jam into’ is frequently used as a 接尾語（せつびご） (suffix) to convey several different meanings. The primary meanings are as follows:
(A) 込（こ）む - To enter completely into doing (A), or the state of being in (A).
(A) 込（こ）む - To enter a state of doing (A) that will not be considered complete until ‘success’.
(A) 込（こ）む - To enter a state of doing (A) that cannot be escaped from.
In this lesson, we will exclusively focus on the first meaning, which is usually translated as ‘to put into (A)’, or ‘to go into (A)’. This form will be attached to the 連用形（れんようけい） (conjunctive form) of other verbs.

• ピンを壁（かべ）に押（お）し込（こ）む。
  To push a pin into a wall.
• 薬（くすり）を飲（の）み込（こ）むのが苦手（にがて）です。
  I am not the best at drinking down medicine. (I am not the best at swallowing medicine)
• 電車（でんしゃ）のドアが閉（し）まる前（まえ）に、電車（でんしゃ）に走（はし）り込（こ）んだ。
  Before the train door closed, I ran in.
• サウナから出（で）て、水風呂（みずぶろ）に飛（と）び込（こ）むように入（はい）った。
  I came out of the sauna and went into the water bath as if I was leaping into it.

Despite the multiple meanings, 込（こ）む can almost always be thought of as ‘jamming (B) into (A)’. This means that whatever the (A) action is, will be something that is not easily entered, but also not easily escaped from.