Why is the Ottoman Empire called "Ottoman" in english?

by sheehanmilesk

Okay, so the Ottoman empire is named after its founder, Osman the First. In Turkish, this makes more sense, with the empire being calledʿOsmānīye and the founder being, well, Osman. Osman, the founder of Osman's Empire. However, in English, we change the name of the empire to Ottoman, but the founder is still known as Osman. Wouldn't it make more sense to either moderately anglicize the empire's name to keep the connection obvious (Osmaniye and Osman) or to alter both their names to keep the connection obvious? (Ottoman the First, founder of the Ottoman Empire.)

i-tiresias

Osman is the Turkish rendering of the Arabic name ‘عثمان’ (‘uthmān), which entered Medieval Latin as ‘ottomānus’, and French as ‘Ottoman’, that being the origin of the adjective that we use.

Source: Concise Oxford Dictionary of English Etymology (OUP:Oxford, 2003)