ae·ci·um 
(ēsē-əm, ēshē-)
(ēsē-əm, ēshē-)n. pl. ae·ci·a (-sē-ə, -shē-ə)
A cuplike structure of some rust fungi that contains chains of aeciospores.
[New Latin, from Greek aikiā, injury, from aikēs, unseemly, injurious : a-, not; see A-1 + eikenai, to seem, be seemly.]
aeci·al (ēsē-əl, -shē-) adj.