The word “compel” has Latin bits that mean “to drive together.” In Latin, compellere meant “to drive together,” often “to drive (cattle) all together.”
In English, for hundreds of years, to compel someone to do something has meant to urge them to do it, or even to force them to do it.
Part of speech:
Verb, the transitive kind: “The story’s quick pace compels us to pay attention;” “I felt compelled to do that;” “He was compelled to go.”
Other common forms:
The other verb forms are “compelled” and “compelling.”
Interestingly, there are two adjective forms (“compelling” and “compulsory“) with very different meanings.
“Compulsory” means “required, mandatory, must-do,” as in “Education is compulsory in the US” and “Training is compulsory before you begin this job.”
And “compelling” means “persuasive, inspiring, effective, irresistible,” as in “His argument is absolutely compelling“ and “There’s no compelling evidence for that theory.”
how to use it:
Pick the formal, very common word “compel” to point out how people did or said certain things because they felt they had no choice.
Most often, we use the passive voice: “He felt compelled to lie to avoid seeming rude;” “She was compelled to quit the team after such a shameful performance.”
But we can also use the active voice: “Good manners compelled him to lie;” “Her shameful performance compelled her to quit the team.”
To use the adjective “compelling” (meaning “irresistible“), talk about compelling ideas, suggestions, data, arguments, reasons, evidence, etc.
And to use the adjective “compulsory” (meaning “required“), talk about compulsory fees, reading, assignments, attendance, education, training, etc.
“Never had the land given forth such harvests as it had this year. He was compelled to build yet another room to the house to store his harvests in, or they would not have had space to walk in the house.”
— Pearl S. Buck, The Good Earth, 1931
“She smiles, but on her the expression looks compulsory, like she’s just adhering to a social convention.”
— Veronica Roth, Allegiant, 2013