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Dictionary.com
Definitions

flu

[floo] / flu /
NOUN
ailment
Synonyms
STRONGEST
ache condition disease disorder illness malady syndrome
STRONG
bug complaint dose indisposition infirmity
Antonyms
STRONGEST
health
NOUN
disease
Synonyms
STRONGEST
Cancer bug condition contamination defect disorder epidemic fever illness infection inflammation malady plague sickness stroke syndrome virus
STRONG
ache affection attack blight breakdown canker collapse complaint contagion convulsions debility decrepitude distemper endemic feebleness fit hemorrhage indisposition infirmity misery seizure spell temperature unhealthiness unsoundness upset visitation
WEAK
ill health pathosis sickliness
Antonyms
STRONGEST
advantage good health health
STRONG
ability blessing boon happiness soundness strength
NOUN
illness
Synonyms
STRONGEST
ailment breakdown collapse disability disorder disturbance ill health malady relapse seizure sickness syndrome virus
STRONG
affliction attack bug complaint confinement convalescence dose fit indisposition infirmity malaise prostration
WEAK
ailing diseasedness failing health poor health unhealth what's going around
Antonyms
STRONGEST
health order
STRONG
aid good health healthiness
WEAK
well-being wellness
NOUN
indigestion
Synonyms
STRONGEST
heartburn nausea
STRONG
acidosis dyspepsia flatulence gas pain
WEAK
acid indigestion digestive upset dyspepsy gaseous stomach
NOUN
infection
Synonyms
STRONGEST
bug disease epidemic pollution virus
STRONG
contagion corruption defilement germs impurity poison
WEAK
communicability contagiousness insanitation septicity what's going around
Antonyms
WEAK
sanitation sterility
NOUN
infirmity
Synonyms
STRONGEST
affliction ailment deficiency frailty ill health imperfection malady
STRONG
confinement debilitation debility decay decrepitude defect disease disorder failing fault feebleness indisposition malaise shortcoming unhealthiness unwellness vulnerability
WEAK
ailing diseasedness sickliness unhealth
Antonyms
STRONGEST
health perfection
STRONG
ability advantage improvement soundness strength strong point
WEAK
good health healthiness robustness
NOUN
insubstantiality
Synonyms
STRONG
affliction ailment confinement debilitation debility decay decrepitude defect deficiency delicacy disease disorder failing fault feebleness flimsiness fragility frailness frailty imperfection indisposition malady malaise puniness shortcoming unhealthiness unsoundness unwellness vulnerability weakness
WEAK
ailing delicateness diseasedness fragileness ill health sickliness unhealth unsubstantiality weakliness
Antonyms
STRONG
ability advantage health improvement perfection soundness strength strong point
NOUN
malady
Synonyms
STRONGEST
Cancer ache affliction ailment blight disability disorder epidemic fever illness infection infirmity inflammation sickness syndrome virus
STRONG
affection attack bug complaint condition contagion debility distemper plague
WEAK
ill health
Antonyms
STRONGEST
comfort good health health relief strength
NOUN
puniness
Synonyms
STRONG
affliction ailment confinement debilitation debility decay decrepitude defect deficiency delicacy disease disorder failing fault feebleness flimsiness fragility frailness frailty imperfection indisposition insubstantiality malady malaise shortcoming unhealthiness unsoundness unwellness vulnerability weakness
WEAK
ailing delicateness diseasedness fragileness ill health sickliness unhealth unsubstantiality weakliness
Antonyms
STRONG
ability advantage health improvement perfection soundness strength strong point
NOUN
unsoundness
Synonyms
STRONG
affliction ailment confinement debilitation debility decay decrepitude defect deficiency delicacy disease disorder failing fault feebleness flimsiness fragility frailness frailty imperfection indisposition insubstantiality malady malaise puniness shortcoming unhealthiness unwellness vulnerability weakness
WEAK
ailing delicateness diseasedness fragileness ill health sickliness unhealth unsubstantiality weakliness
Antonyms
STRONG
ability advantage health improvement perfection soundness strength strong point
NOUN
unsubstantiality
Synonyms
WEAK
affliction ailing ailment confinement debilitation debility decay decrepitude defect deficiency delicacy delicateness disease diseasedness disorder failing fault feebleness flimsiness fragileness fragility frailness frailty ill health imperfection indisposition insubstantiality malady malaise puniness shortcoming sickliness unhealth unhealthiness unsoundness unwellness vulnerability weakliness weakness
NOUN
weakliness
Synonyms
WEAK
affliction ailing ailment confinement debilitation debility decay decrepitude defect deficiency delicacy delicateness disease diseasedness disorder failing fault feebleness flimsiness fragileness fragility frailness frailty ill health imperfection indisposition insubstantiality malady malaise puniness shortcoming sickliness unhealth unhealthiness unsoundness unsubstantiality unwellness vulnerability weakness

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

But inside at least one hospital, the mood, helped by evidence that flu was easing, was strikingly different.

From BBC • Apr. 13, 2026

Older adults are far more likely to develop severe illness from flu or COVID, and new research from UC San Francisco offers an explanation.

From Science Daily • Apr. 3, 2026

Becerra pointed to his experiences leading the sprawling federal health agency in the Biden administration, including dealing with the COVID-19 pandemic, the wildfires that devastated Maui, Hawaii, avian flu and monkey pox.

From Los Angeles Times • Apr. 1, 2026

What has helped is that the threat of highly pathogenic avian influenza, or bird flu, has faded.

From MarketWatch • Apr. 1, 2026

As we all know from experience, there are some illnesses, such as flu and the common cold, to which our resistance is only temporary; we can eventually contract the illness again.

From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond