hemarthrosis
noun
he·mar·thro·sis
variants:
or chiefly British haemarthrosis \ ˌhē-mär-ˈthrō-səs 
, ˌhem-är-
\
, ˌhem-är-
\
plural hemarthroses\ -ˌsēz
\
\
Medical Definition of hemarthrosis
: hemorrhage into a joint