We found 11 dictionaries that define the word reactiveness:

General (7 matching dictionaries)

1. reactiveness: Merriam-Webster
2. reactiveness: Collins English Dictionary
3. reactiveness: Wordnik
4. reactiveness: Wiktionary
5. reactiveness: Dictionary.com
6. reactiveness: FreeDictionary.org
7. reactiveness: TheFreeDictionary.com

Business (1 matching dictionary)

8. reactiveness: Legal dictionary

Computing (1 matching dictionary)

9. reactiveness: Encyclopedia

Medicine (2 matching dictionaries)

10. reactiveness: Merriam-Webster Medical Dictionary
11. reactiveness: Medical dictionary

(Note: See reactive as well.)

Definitions from Wiktionary (reactiveness) ▸ noun:  The quality or state of being reactive. Similar: responsiveness, reactionariness, responsitivity, activeness, reflexiveness, adaptiveness, reflectiveness, reflexibility, unreactiveness, reflexness, more... Opposite: proactivity, initiative, assertiveness ▸ Words similar to reactiveness ▸ Usage examples for reactiveness ▸ Idioms related to reactiveness ▸ Wikipedia articles (New!) ▸ Popular adjectives describing reactiveness ▸ Words that often appear near reactiveness ▸ Rhymes of reactiveness ▸ Invented words related to reactiveness