From The Collaborative International Dictionary of English v.0.48 :
Miliaria \Mil`i*a"ri*a\, n. [NL. See Miliary.] (Med.)
A fever accompanied by an eruption of small, isolated, red
pimples, resembling a millet seed in form or size; miliary
fever.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
miliaria
n 1: obstruction of the sweat ducts during high heat and
humidity [syn: prickly heat, heat rash, miliaria]