We found 28 dictionaries that define the word instantaneous:

General (25 matching dictionaries)

1. instantaneous: Merriam-Webster
2. instantaneous: Oxford Learner's Dictionaries
3. instantaneous: American Heritage Dictionary of the English Language
4. instantaneous: Collins English Dictionary
5. instantaneous: Vocabulary.com
6. Instantaneous, instantaneous: Wordnik
7. instantaneous: Cambridge Advanced Learner's Dictionary
8. instantaneous: Wiktionary
9. instantaneous: Webster's New World College Dictionary, 4th Ed.
10. instantaneous: The Wordsmyth English Dictionary-Thesaurus
11. instantaneous: Infoplease Dictionary
12. Instantaneous, instantaneous: Dictionary.com
13. instantaneous: Cambridge Essential American English Dictionary
14. Instantaneous: Wikipedia, the Free Encyclopedia
15. Instantaneous: Online Plain Text English Dictionary
16. instantaneous: Webster's Revised Unabridged, 1913 Edition
17. instantaneous: Rhymezone
18. instantaneous: Webster's 1828 Dictionary
19. instantaneous: FreeDictionary.org
20. instantaneous: Mnemonic Dictionary
21. instantaneous: TheFreeDictionary.com
22. Instantaneous: AllWords.com Multi-Lingual Dictionary
23. instantaneous: Longman Dictionary of Contemporary English

Business (1 matching dictionary)

24. instantaneous: Legal dictionary

Computing (1 matching dictionary)

25. instantaneous: Encyclopedia

Medicine (1 matching dictionary)

26. online medical dictionary (No longer online)

(Note: See instantaneity as well.)

Definitions from Wiktionary ( ) ▸ adjective:  Occurring, arising, or functioning without any delay; happening within an imperceptibly brief period of time. Similar: instant, fast, immediate, present, presentaneous, timely, imminent, just-in-time, prompt, pretemporal, more... Opposite: gradual, slow, leisurely Types: immediate, prompt, speedy, quick, fast, more... Phrases: instantaneous velocity, instantaneous rate, instantaneous frequency, instantaneous speed, instantaneous center, more... Colors:     electric blue,     neon green,     vivid yellow,     hot pink,     lime green, more... ▸ Words similar to instantaneous ▸ Usage examples for instantaneous ▸ Idioms related to instantaneous ▸ Wikipedia articles (New!) ▸ Popular nouns described by instantaneous ▸ Words that often appear near instantaneous ▸ Rhymes of instantaneous ▸ Invented words related to instantaneous