up one's ears (adjective) busy: engaged, at work
Sinonime: active, already taken,
assiduous, at it, buried,
diligent,
employed,
engaged,
engrossed, having a full plate, having enough on one's plate, having fish to fry, having many irons in the fire, hustling, in a meeting, in conference, in someone else's possession, in the field, in the laboratory,
industrious,
occupied, on assignment, on duty, on the go, overloaded,
persevering, slaving, snowed, swamped, tied up,
unavailable, up to one's ears, with a customer,
workingAntonime: idle,
quiet, unbusy, unemployed, unengaged