also die-hard, 1844 (n.), in reference to the 57th Regiment of Foot in the British Army; as an adjective, attested from 1871; from die (v.) + hard (adv.). As a brand name of an automobile battery, DieHard, introduced by Sears in 1967.
1. diehard supporters of the exiled king
2. Not even their diehard supporters can pretend that this was a great game.
3. He was much annoyed at my remark and called me a diehard.
4. Though there are always predictable throngs of diehard Beatles fans and classic?