Simple past tense and past participle of redden.(verb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "reddened" in a sentence
"There was panic in his big blue eyes, and his face reddened from the exertion as he struggled."
"Withal there were many warriors amongst the throng, and most of these bore a token on their sleeves, to wit, a sword reddened with blood."
"The quantity of alkaline matter diminished in every operation; and in the last process, though the battery had been kept in great activity for three days, the fluid possessed, in a very slight degree, only the power of acting on paper tinged with turmeric; but its alkaline property was very sensible to litmus paper slightly reddened, which is a much more delicate test; and after evaporation and the process by carbonate of ammonia, a barely perceptible quantity of fixed alkali was still left."