esthesiometer
noun
es·the·si·om·e·ter
variants:
or chiefly British aesthesiometer \ es-ˌthē-zē-ˈäm-ət-ər 
, -ˌthē-sē-
\
, -ˌthē-sē-
\
Medical Definition of esthesiometer
: an instrument for measuring sensory discrimination
especially
: one for determining the distance by which two points pressed against the skin must be separated in order that they may be felt as separate