Low-key
American SlangDefinition
Understated or restrained; done, felt, or intended quietly without drawing attention; to a slight or moderate extent.
Examples
"We kept the birthday low-key, just a quiet dinner with family and a small cake."
"I’m low-key excited about the new project, but I don’t want to make a big deal out of it."
"They planned a low-key wedding in their backyard to avoid drawing attention."