Deliberately, as a matter of preference. For example, No one told me to come; I'm here by choice. This expression replaced the earlier with choice, used from about 1500.
Words nearby by choice
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.