Olog-hai is a term out of the Black Speech. Olog means "troll" and hai (as in Uruk-hai) means "folk".
Black Speech
-hai
suffix. folk
oghor-hai
noun. Wose-folk
olog-hai
noun. Troll-folk
uruk-hai
noun. Orc-folk
hai
suffix. folk, people
Olog-hai
Olog-hai
Uruk-hai
Uruk-hai
The name Uruk-hai has the element uruk, which is a Black Speech word meaning "Orc". (For related words in other languages, see Orcs in Tolkien's languages.) The element -hai, also present in Olog-hai and Oghor-hai, means "folk, people".
Oghor-hai
Oghor-hai
oghor + hai
This word can be found in a combination with the word uruk making uruk-hai meaning orc-folk. >> -hai.