Etymology Map
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Theory

3 stages from Greek to English.

Today it means a system of ideas explaining something

Where does the word "theory" come from? It comes from Greek theōria, passing through Late Latin before entering English (1590s).

1
Stage 1 of 3
theōria
Greek · ancient
"contemplation, viewing"
from 'theōros', spectator; related to 'theatre'
2
Stage 2 of 3
theoria
Late Latin · ancient
"speculation"
used for speculative thought
3
Stage 3 of 3
theory
English · 1590s
"an explanatory idea"
in science, a well-tested explanation, not a guess
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Read the full story

Theory’s story begins in Greek: theōria meant “contemplation, viewing.” From 'theōros', spectator; related to 'theatre'. By ancient, the word had taken hold in Late Latin as theoria. Used for speculative thought. It reached English by 1590s as theory. In science, a well-tested explanation, not a guess. Today, theory means a system of ideas explaining something.