-logist Also -loger.
A person skilled in, or involved in, a branch of study.
Many examples exist, of which a few are archaeologist, biologist, entomologist, futurologist, geologist, meteorologist, ornithologist, pathologist, psychologist, technologist, and zoologist. The form is actively used to make new words as required.
At one time, the form -loger with the same sense was common (see -er1), but most examples have been replaced by others in -logist. A rare surviving example is astrologer.