"authority to command the national military forces," in extended use "an empire," 1650s, from Latin imperium "command, supreme authority, power" (see empire). Hence Latin phrase imperium in imperio "a state within a state."
1711 in the political sense, "the first minister of a state," a shortening of premier minister (1680s); see premier (adj.). In U.S. usage, premier formerly was applied occasionally to the Secretary of State (late 19c.).
word-forming element expressing state or condition, in medical terminology denoting "a state of disease," from Latin -osis and directly from Greek -osis, formed from the aorist of verbs ending in -o. It corresponds to Latin -atio.