Picking a weak synonym starts with one question: weak in what way? A tired body is feeble or frail, a cheap shelf is flimsy or fragile, a light is faint, and a poor excuse is unconvincing.
English has a sharp word for each case, and using the precise one makes your writing clearer than the general adjective. Some choices are kind, some are harsh, and a few can insult a person, so the notes below flag tone as well as meaning.
Swatch at a glance
Best swaps
feeble, frail, fragile, flimsy, faintPart of speech
AdjectiveMost formal
infirm, debilitated, ineffectualMost casual
wobbly, puny, shakyHarshest
spineless, patheticAntonyms
strong, sturdy, robustWatch out
Lame for a weak excuse is slang and can hurt people with a disability. Prefer thin or unconvincing.Word forms covered
weaker, weakest, weakly, weakness, weaken
Six kinds of weakness, six word sets
| What is weak | Try | Quick example |
|---|---|---|
| A person after illness | frail, feeble, drained, shaky | Grandpa felt shaky after the fever. |
| A structure or object | flimsy, rickety, fragile, brittle | That rickety ladder needs replacing. |
| An argument or excuse | unconvincing, thin, hollow | His reason for missing class was thin. |
| A leader or decision | indecisive, ineffectual, timid | The board gave an ineffectual reply. |
| Coffee, light or sound | watery, dim, faint, muted | A faint signal kept dropping out. |
| A school subject | poor, rusty, shaky on | I am rusty at long division. |
From shaky to helpless: how strong is the word
The chip strip shows rising degrees of physical weakness. Shaky is brief and minor; you might feel shaky after skipping lunch. Delicate suggests a need for gentle handling. Frail often describes older people or long illness and carries sympathy. Feeble is lower still and can sound slightly dismissive. Helpless means unable to act at all.
Tone matters as much as degree. Frail is caring, puny is mocking, and pathetic is an insult. Let the word reflect your attitude toward the person.
Trading weak for something sharper: a weak synonym in action
- The bridge looked weak becomes the bridge looked unsound.
- She gave a weak smile becomes she gave a faint smile.
- A weak argument becomes a flimsy argument or an unpersuasive case.
- The tea is weak becomes the tea is watery.
- He is weak after surgery becomes he is frail after surgery.
- My math is weak becomes my math is shaky.
A student edits an essay: "The author's evidence is weak." Swapping to "The author's evidence is thin and mostly anecdotal" tells the marker exactly what is wrong, which earns more credit than a vague label.
Weakness, weaker and weaken
The noun weakness has two senses. For a flaw, try shortcoming, failing, flaw or blind spot. For a liking, try soft spot, fondness or love of: "a weakness for chocolate" becomes "a soft spot for chocolate."
The comparative weaker swaps with less robust or frailer. The verb weaken pairs with undermine, sap, erode and water down. In interviews, "What is your biggest weakness?" is often answered with "an area I am working on", which sounds more constructive.
Words to handle with care
Spineless and gutless are personal attacks; keep them out of reviews and formal feedback. Lame is common slang for a dull or weak thing, but it began as a word for a disability and many readers find it unkind. Vulnerable is not a full synonym: it means open to harm, and that openness can be a strength in honest writing. See the vulnerable synonyms page for that sense. Soft works for lenient rules but sounds informal.
Opposite words with examples
The direct antonym is strong. For objects use sturdy or solid; for systems and health use robust; for arguments use convincing or compelling; for a person's character, firm or resolute.
- We bought a sturdy table this time.
- Her proposal for a four-day week was compelling.
For more contrasts, browse powerful synonyms or our full adjective collection.
Frequently asked questions
Which formal words can stand in for weak?
Infirm suits health writing, ineffectual suits decisions and policies, and unsound suits structures or reasoning. Pick by what is weak.
How do I call someone weak without being rude?
Frail and delicate are gentle and sympathetic. For skills, say someone is still building confidence or is less experienced.
How should I label a feeble argument?
Unconvincing, flimsy, thin and unpersuasive work well. Hollow suggests it sounds good but has nothing behind it.
Is fragile a synonym for weak?
Yes, for objects and sometimes moods. Fragile stresses that something breaks easily, while weak is broader and can mean low in power.
What is the opposite of weak?
Strong is the main opposite. Sturdy, robust, powerful and solid fit specific cases such as furniture, health or arguments.
How do I describe weak coffee or tea?
Watery, thin and diluted are the usual choices. Mild is kinder and fits drinks that are light by design.