masochistnoun [ C ]
us/ˈmæs·ə·kɪst/a person who gets pleasure from being hurt by another person
masochism
noun [ U ] us/ˈmæs·əˌkɪz·əm/
masochistic
adjective [ not gradable ] us/ˌmæs·əˈkɪs·tɪk/
fig. Running in ultramarathons seems somewhat masochistic to me.