electorate (n.)

"one who elects or has the right of choice," mid-15c., from Latin elector "chooser, selecter," agent noun from past-participle stem of eligere "to pick out, choose" (see election).

word-forming element used in forming nouns from Latin words ending in -atus, -atum (such as estate, primate, senate). Those that came to English via French often arrived with -at, but an -e was added after c. 1400 to indicate the long vowel. The suffix also can mark adjectives formed from Latin past participles in -atus, -ata (such as desolate, moderate, separate); again, they often were adopted in Middle English as -at, with an -e appended after c. 1400.