What is the meaning of hard-on?

possible profanity

noun

14
 
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APAWordNet. (2010). hard-on. Retrieved August 17, 2017, from http://smartdefine.org/hard-on/definitions/1284104
ChicagoWordNet. 2010. "hard-on" http://smartdefine.org/hard-on/definitions/1284104 (accessed August 17, 2017).
HarvardWordNet 2010, hard-on, Smart Define, viewed 17 August, 2017, <http://smartdefine.org/hard-on/definitions/1284104>.
MLAWordNet. "hard-on" 23 October 2010. Web. 17 August 2017. <http://smartdefine.org/hard-on/definitions/1284104>