We found 19 dictionaries that define the word infectiousness:

General (14 matching dictionaries)

1. infectiousness: Merriam-Webster
2. infectiousness: Oxford Learner's Dictionaries
3. infectiousness: Collins English Dictionary
4. infectiousness: Wordnik
5. infectiousness: Wiktionary
6. Infectiousness, infectiousness: Dictionary.com
7. Infectiousness: Online Plain Text English Dictionary
8. infectiousness: Webster's Revised Unabridged, 1913 Edition
9. Infectiousness: AllWords.com Multi-Lingual Dictionary
10. infectiousness: Webster's 1828 Dictionary
11. infectiousness: FreeDictionary.org
12. infectiousness: TheFreeDictionary.com

Business (1 matching dictionary)

13. infectiousness: Legal dictionary

Computing (1 matching dictionary)

14. infectiousness: Encyclopedia

Medicine (3 matching dictionaries)

15. infectiousness: Merriam-Webster Medical Dictionary
16. online medical dictionary (No longer online)
17. infectiousness: Medical dictionary

(Note: See infectious as well.)

Definitions from Wiktionary (infectiousness) ▸ noun:  The state or condition of being infectious. Similar: infectiveness, contagiousness, infectedness, uninfectiousness, transmissibility, noninfectiousness, communicableness, transfectability, virulence, poisonability, more... Opposite: noninfectiousness, immunity, resistance, insusceptibility ▸ Words similar to infectiousness ▸ Usage examples for infectiousness ▸ Idioms related to infectiousness ▸ Wikipedia articles (New!) ▸ Popular adjectives describing infectiousness ▸ Words that often appear near infectiousness ▸ Rhymes of infectiousness ▸ Invented words related to infectiousness