- First or highest in rank, quality, or importance; principal. (adjective)
- Being or standing first in a list, series, or sequence. (adjective)
- Occurring first in time or sequence; earliest. (adjective)
- Being or existing as the first or earliest of a kind; primitive. (adjective)
- Geology Characteristic of or existing in a rock at the time of its formation. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.