Simple past tense and past participle of thumb.(verb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "thumbed" in a sentence
"He did not use it to chase his assailant away, but without a word thumbed off the safety and shot the would-be thief dead in the head."
"Probably many of these _incognita_ and _rarissima_ perished in the great fire of London; others again met their fate solely through their own popularity, being 'thumbed' to pieces."
"For example, the distributional tables outlining the impact of the GST were the most 'thumbed' part of the documentation, certainly by those Treasury officers answering phone queries."