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"principal" is also used as a crossword clue. If that's what you saw, the answer is often main (4 letters).
Definitions
most important element
Word origin
From Middle English principal, from Old French principal, from Latin prīncipālis.
Used in a sentence
“Smith is the principal architect of this design.”
“The principal cause of the failure was poor planning.”
“For many years, Oslo had no railway communication with Bergen and Stavanger, the principal seaports on the south-west coast.”
Source: Wiktionary, CC BY-SA 4.0
Used as a crossword answer2 curated clues
01“school head”9 letters
02“Main or most important”9 letters
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