Check Up, Checkup or Check-Up - Which One to Use?
Checkup: When it’s a single word like this, it’s a noun to describe an appointment. “I have a checkup at the dentist later this month.”
Check-up: Add in the hyphen, and it becomes a phrasal adjective meant to describe the type of appointment or something. “My check-up appointment is at two o’clock, Thursday.”
Check up: If used as two individual words, you’ve got yourself a verb to describe what you’re doing, aka a phrasal verb. “I’m going to check up on my dad later this week and ensure he’s okay.”