to hold together or press in from every side: to hold shut, hem in, grip, or drive onward
At its root the word means to hold things together, to keep them from coming apart or getting loose. From that one picture the New Testament draws a whole family of uses, each of them some form of holding or pressing in.
The plainest uses are physical: holding a prisoner in hand (Luke 22:63) or holding the ears shut (Acts 7:57). Close beside these is the idea of pressing in from around, whether a crowd packed tight against a person (Luke 8:45) or an army closing in on a city under siege (Luke 19:43).
The same image turns inward when something takes hold of a person and will not let go: a fever, a disease, or a wave of fear (Luke 4:38; Luke 8:37). At its strongest it names an inner force that grips and drives, as when the love of Christ leaves Paul no other course (2 Corinthians 5:14) or he feels squeezed between two good options (Philippians 1:23).
Greek has a close cousin in κατέχω, which also builds on the idea of holding, but leans toward holding down, holding back, or holding fast to something, where this word leans toward holding together and pressing in from every side.