Simple past tense and past participle of know.(verb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "know'd" in a sentence
"Joy used to come here and just not say a word, she was so depressed, so worried, you know how it is, like she was so distracted and worried she couldn't even look at you, and bags under her eyes, and I know'd she wasn't sleeping."
"I know'd Joy since she was ... oh, eleven or twelve."
"I wouldn't ask my mother to go because I know'd she wouldn't let me go."