At an indefinite time in the future.
Usage Note: The adverbs someday and sometime express future time indefinitely: We'll succeed someday. Come sometime. Let's meet sometime when your schedule permits. This sense can also be conveyed by some day and some time. The two-word forms are always used when some is an adjective modifying and specifying a more particular day or time: Come some day (not someday) soon. Choose some day (not someday) that is not so busy. See Usage Note at sometime.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.