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Webster 1913 Edition

Adj.

Governed by one’s own will; not yielding to the wishes of others; obstinate.

Adj.

Governed by one's own will; not yielding to the will or wishes of others; not accomodating or compliant; obstinate.

self-willed ‎(comparative more self-willed, superlative most self-willed)

Obstinate; strong-minded
He was so self-willed that he refused to do anything that did not grant instant satisfaction.
Possessing self-will.
The idea of self-willed machines, which could decide to take over the world, scares all the people smart enough to create such devices.