Noun
A smaller, more specialized area of study or occupation within a larger one
(algebra) A subring of a field, containing the multiplicative identity and closed under inversion.
Source: en.wiktionary.orgBriefly, the basefield has to contain an ordered subfield in order for non-negativity to make sense, citation. Source: Internet
Although Davis's theory is not entirely accurate, it was absolutely revolutionary and unique in its time and helped to modernize and create Geography subfield of Geomorphology. Source: Internet
Convex minimization is a subfield of optimization that studies the problem of minimizing convex functions over convex sets. Source: Internet
Although such controllers need not be electrical many are and hence control engineering is often viewed as a subfield of electrical engineering. Source: Internet
A subfield of marine biology studies the relationships between oceans and ocean life, and global warming and environmental issues (such as carbon dioxide displacement). Source: Internet
Every computable real number is arithmetical, and the arithmetical numbers form a subfield of the reals, as do the analytical numbers. Source: Internet