A subdivision of a field of study; a subdiscipline.(noun)
Mathematics A field that is a subset of another field.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "subfield" in a sentence
"I do research in computer science, in the formal semantics of programming languages, and it looks like my subfield is on the verge of a phase change -- I think that very soon paper proofs of theorems will stop being acceptable for publication; we will have to submit formal, machine-checked proofs."
"Survey of computational scientists in the subfield of machine learning, sampling American academics registered at the top Machine Learning conference, students and professors."
"Victoria did a study of one particular subfield: Machine Learning."