Answer:
A prefix.
Examples:
Bio-logy: The prefix bio means life, and the suffix ology means the study/field of. Combined they give the meaning; the study of life.
Hydro-philic: The prefix hydro means water, and the suffix philic means the love of. Combined the give the meaning; water loving.
Astro-logy: The prefix astro means star, and the suffix ology means the study/field of. Combined they give the meaning; the study of stars.
