To form a notion or idea in the mind; to fancy. We can imagine the figure of a horse’s head united to a human body. In this sense, fancy is the more proper word.

To form ideas or representations in the mind, by modifying and combining our conceptions.

To contrive in purpose; to scheme; to devise. How long will ye imagine mischief against a man? Psalm 62:3.

To conceive; to have a notion or idea. I cannot imagine how this should have happened.