Definition of perosmic in US English:
perosmic
adjective
Chemistry
Of osmium in its highest oxidation state (8). Chiefly in "perosmic acid"noun = "osmium tetroxide", "osmic acid".
Origin
Late 19th century; earliest use found in The Athenaeum. From per- + osmic.
Pronunciation
perosmic
/pəˈrɒzmɪk/