Meanings
adjectiveinfectious (comparative more infectious, superlative most infectious)
comparative more infectious · superlative most infectious
- medicineCaused by an agent that enters the host's body (such as a bacterium, virus, parasite, or prion); often, also, transmitted among hosts via any of various routes (for example, contact, droplet-borne, airborne, waterborne, foodborne, fomite-borne, or bloodborne).
Cancer is usually not infectious.
1 more example
More infectious diseases like the flu are usually less potent.
- typically of a personmedicineAble to infect others; capable of transmitting pathogens.
Despite feeling better, the patient is still infectious.
1 more example
I doubt that [saliva] is very infectious ... I don't think this is a normal route of transmission.
1981 December 1, Sue Hyde, quoting Paul Black, “AIDS Update: Little To Cheer About”, in Gay Community News, volume 12, number 20, page 3 - Spreading quickly from one person to another.
infectious smile
2 more examples
Her enthusiasm for work can be really infectious.
When Maisie first met Danny, she remembers that he had an infectious laugh and a love for music.
2024 November 20, Fortesa Latifi, “How These Men Left the Manosphere — and Why Some May Never”, in Teen Vogue - informalMemorable and invoking excitement or interest.
Pop music is more infectious than elevator music.
Synonyms & antonyms
Opposite
adjectiveeasily spread
Opposite
Synonym sets from Open English WordNet, CC BY 4.0.
Origin
- New Latinīnfectiōsus
- Englishinfectious
Borrowed from New Latin īnfectiōsus. By surface analysis, infect + -ious.
More words from New Latin
Full word history & related roots →Translations
Arabic مُعْدٍ, مُعْدٍ
- مُعْدٍ (muʕdin)able to infect others
- مُعْدٍ (muʕdin)(of feelings and behaviour) spreading quickly between persons
- مُعْدٍ (muʕdin)transmitted between persons as illness
Bengali সংক্রামক, ছোঁয়াচে
- সংক্রামক (śoṅkramok)transmitted between persons as illness
- ছোঁয়াচে (chō̃ẇace)transmitted between persons as illness
Bulgarian заразен, инфекциозен
- заразен (zarazen)able to infect others
- инфекциозен (infekciozen)able to infect others
- инфекциозен (infekciozen)(of feelings and behaviour) spreading quickly between persons
- заразителен (zarazitelen)informal: memorable and invoking excitement or interest
- заразен (zarazen)transmitted between persons as illness
Catalan infecciós, infecciós
- infecciósable to infect others
- infecciós(of feelings and behaviour) spreading quickly between persons
- infeccióstransmitted between persons as illness
Czech nakažlivý, nakažlivý
- nakažlivýable to infect others
- nakažlivýinformal: memorable and invoking excitement or interest
- nakažlivýtransmitted between persons as illness
- infekčnítransmitted between persons as illness
Dutch aanstekelijk, aanstekelijk
- aanstekelijk(of feelings and behaviour) spreading quickly between persons
- aanstekelijkinformal: memorable and invoking excitement or interest
Esperanto infekta
- infektatransmitted between persons as illness
Finnish tartuntavaarallinen, tarttuva
- tartuntavaarallinenable to infect others
- tarttuva(of feelings and behaviour) spreading quickly between persons
- tarttuvainformal: memorable and invoking excitement or interest
- tarttuvatransmitted between persons as illness
- tartuntavaarallinentransmitted between persons as illness
French contagieux, communicatif
- contagieuxable to infect others
- communicatif(of feelings and behaviour) spreading quickly between persons
- infectieuxtransmitted between persons as illness
German infektiös, ansteckend
- infektiösable to infect others
- ansteckend(of feelings and behaviour) spreading quickly between persons
- infektiöstransmitted between persons as illness
Hindi संक्रामक
- संक्रामक (saṅkrāmak)transmitted between persons as illness
Icelandic smitandi
- smitandi(of feelings and behaviour) spreading quickly between persons
Indonesian infeksius, menular
- infeksiusable to infect others
- menularable to infect others
- viral(of feelings and behaviour) spreading quickly between persons
- infeksiustransmitted between persons as illness
- menulartransmitted between persons as illness
Irish ionfhabhtaíoch, tógálach
- ionfhabhtaíochable to infect others
- tógálachtransmitted between persons as illness
Italian infettivo, contagioso
- infettivoable to infect others
- contagiosoable to infect others
- infettivotransmitted between persons as illness
Japanese 感染性
- 感染性transmitted between persons as illness
Malay berjangkit, berjangkit
- berjangkitable to infect others
- berjangkit(of feelings and behaviour) spreading quickly between persons
- berjangkittransmitted between persons as illness
Māori hōrapa, hōrapa
- hōrapaable to infect others
- hōrapa(of feelings and behaviour) spreading quickly between persons
- ngahau(of feelings and behaviour) spreading quickly between persons
- hōrapatransmitted between persons as illness
- hopuhoputransmitted between persons as illness
Norwegian Bokmål smittsom, smittsom
- smittsomable to infect others
- smittsom(of feelings and behaviour) spreading quickly between persons
- smittsomtransmitted between persons as illness
Polish zaraźliwy, zaraźliwy
- zaraźliwy(of feelings and behaviour) spreading quickly between persons
- zaraźliwytransmitted between persons as illness
- zakaźnytransmitted between persons as illness
- infekcyjnytransmitted between persons as illness
Portuguese infeccioso, contagioso
- infecciosoable to infect others
- contagiosoable to infect others
- infecciosotransmitted between persons as illness
Romanian infecțios, infecțios
- infecțiosable to infect others
- infecțiostransmitted between persons as illness
Russian зара́зный, зарази́тельный
- зара́зный (zaráznyj)able to infect others
- зарази́тельный (zarazítelʹnyj)(of feelings and behaviour) spreading quickly between persons
- зара́зный (zaráznyj)transmitted between persons as illness
- инфекцио́нный (infekciónnyj)transmitted between persons as illness
Scottish Gaelic gabhaltach
- gabhaltachtransmitted between persons as illness
Spanish infeccioso, contagioso
- infecciosoable to infect others
- contagiosoable to infect others
- infecciosotransmitted between persons as illness
Swedish infektiös, smittande
- infektiösable to infect others
- smittande(of feelings and behaviour) spreading quickly between persons
- infektiöstransmitted between persons as illness
Tagalog nakahahawa, nakahahawa
- nakahahawaable to infect others
- nakahahawatransmitted between persons as illness
Welsh heintus, heintus
- heintusable to infect others
- heintus(of feelings and behaviour) spreading quickly between persons
- heintustransmitted between persons as illness
Cite this entry
APA
infectious. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/infectious
MLA
“infectious.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/infectious. Accessed November 3, 2026.
Chicago
WatkinsX Dictionary, s.v. “infectious,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/infectious.
Source: infectious on Wiktionary, CC BY-SA 4.0.