Let's add another definition (same source):
Main Entry:
the·o·ry
Pronunciation:
\th--r, thir-\
Function:
noun
Inflected Form(s):
plural the·o·ries
Etymology:
Late Latin theoria, from Greek theria, from therein
Date:
1592
1: the analysis of a set of facts in their relation to one another
2: abstract thought : speculation
3: the general or abstract principles of a body of fact, a science, or an art
4 a: a belief, policy, or procedure proposed or followed as the basis of action
b: an ideal or hypothetical set of facts, principles, or circumstances ”often used in the phrase in theory
5: a plausible or scientifically acceptable general principle or body of principles offered to explain phenomena
6 a: a hypothesis assumed for the sake of argument or investigation b: an unproved assumption : conjecture c: a body of theorems presenting a concise systematic view of a subject