not changing or varying; uniform; regular; invariable

All conditions during the three experiments were constant.

continuing without pause or letup; unceasing

constant noise.

regularly recurrent; continual; persistent

He found it impossible to work with constant interruption.

faithful; unswerving in love, devotion, etc.

a constant lover.

steadfast; firm in mind or purpose; resolute.

Obsolete . certain; confident.

something that does not or cannot change or vary.

Physics . a number expressing a property, quantity, or relation that remains unchanged under specified conditions.

Mathematics . a quantity assumed to be unchanged throughout a given discussion.

adverb

steadily , invariably , continually , regularly