We found 16 dictionaries that define the word at one time:

General (15 matching dictionaries)

1. at one time: Merriam-Webster
2. at one time: Oxford Learner's Dictionaries
3. at one time: Collins English Dictionary
4. at one time: Vocabulary.com
5. at (any) one time, at one time: Cambridge Advanced Learner's Dictionary
6. at one time: Wiktionary
7. at one time: Dictionary.com
8. at one time: Rhymezone
9. at one time: FreeDictionary.org
10. at one time: Mnemonic Dictionary
11. at one time: TheFreeDictionary.com
12. at one time: Longman Dictionary of Contemporary English
13. at one time: Merriam-Webster

Miscellaneous (1 matching dictionary)

14. at one time: Idioms

Definitions from WordNet (at one time) ▸ adverb:  at a previous time ▸ adverb:  simultaneously Types: once, formerly, more... Phrases: to eat a lot of food at one time, existed at one time, more... ▸ Words similar to at one time ▸ Usage examples for at one time ▸ Idioms related to at one time ▸ Wikipedia articles (New!) ▸ Words that often appear near at one time ▸ Rhymes of at one time ▸ Invented words related to at one time