algolagnia
noun
al·go·lag·nia ˌal-gō-ˈlag-nē-ə 
: a perversion (such as sadism or masochism) characterized by pleasure and especially sexual gratification in inflicting or suffering pain
algolagniac
ˌal-gō-ˈlag-nē-ˌak
noun 
Word History
Etymology
New Latin, from Greek algos pain + lagneia lust, from lagnos lustful — more at slack
First Known Use
1897, in the meaning defined above
Medical Definition
algolagnia
noun
al·go·lag·nia ˌal-gō-ˈlag-nē-ə
: a perversion (as masochism or sadism) in which pleasure and especially sexual gratification is obtained by inflicting or suffering pain