1. based on sound reasoning or evidence; logically correct
2. legally or officially acceptable; having legal force
3. still in effect; not expired or canceled

Examples

• Her argument was valid and well-supported by evidence.
• You need a valid driver’s license to rent a car.
• The coupon is valid until the end of this month.
• His concerns about the project are completely valid.
• Make sure your passport is still valid before traveling.
• The contract remains valid for another two years.
• That’s not a valid excuse for being late to class.