1. Before a time limit expires
   "the timely filing of his income tax return"
    
2. Done or happening at the appropriate or proper time
   "a timely warning"; "with timely treatment the patient has a good chance of recovery";
   - seasonable, well-timed, well timed

1. At an opportune time
   "your letter arrived timely";
   - seasonably, well-timed, apropos

Derived forms: timeliest, timelier

See also: on the dot, on time, opportune, punctual

Encyclopedia: Timely