to shut oneself in (e.g. one's room); to be confined in; to fill with (emotion, enthusiasm, power, etc.); to imbue with; to fill a space (of a gas, smell, etc.); to be heavy with (e.g. smoke); to be muffled (e.g. of a voice)
to stay indoors; to be confined indoors
to seclude oneself; to shut oneself away
heated (e.g. debate); passionate
to shut oneself in (one's house, room, etc.); to confine oneself (to); to barricade oneself (in a building); to entrench oneself; to hole up
shut-in; stay-at-home; hikikomori; social withdrawal; shunning other people
shutting oneself in (one's room, etc.); barricading oneself in (a fort, etc.) while being besieged; holing up (in a building)