pressing something in under pressure: injecting / (chemistry) forcing / (chemistry) penetration / (chemistry, machining) a press fit / (medicine) an indentation

indent / press into / inject

Entering a stage of enlightenment (such as with Buddhism).

Enter a stage of enlightenment.

inhalation

inhale

intervene, step in (an argument), edge in (a market)

the act of mixing; the state of being mixed; a mixing or mingling of two or more things, typically in an undesirable way

to mix one thing into another, typically in an undesirable way / to mingle, to become mixed, to get mixed, typically in an undesirable way

join, become a member