inefficacious

C2+ Topic:Cause, Change & Process

US /ˌɪnɛfɪˈkeɪʃəs/ UK /ˌɪnɛfɪˈkeɪʃəs/ See IPA manual

adj

Meanings

1

adj
failing to produce the intended effect; ineffective

The old remedy proved inefficacious against the new strain.

Thesaurus

Synonyms

1 adj · failing to produce the... ineffective ineffectual futile fruitless unavailing powerless

Opposites

efficacious effective potent

Word family

Derived forms inefficaciouslyinefficaciousness

Related forms efficacious efficacy effect efficient

Etymology

From in- ('not') + efficacious, from Latin efficax ('effective'), from efficere ('to accomplish'), from ex- ('out') + facere ('to do, make').

efficax Latin facere Latin

View etymology graph ->

Topics

Cause, Change & Process Word Formation & Derivatives

# inefficacious

**Type:** Word
**Level:** C2+
**Part of speech:** adj
**IPA (US):** ˌɪnɛfɪˈkeɪʃəs
**IPA (UK):** ˌɪnɛfɪˈkeɪʃəs

## Meanings
1. failing to produce the intended effect; ineffective

## Examples
- The old remedy proved inefficacious against the new strain.

## Synonyms
- ineffective
- ineffectual
- futile
- fruitless
- unavailing
- powerless

## Antonyms
- efficacious
- effective
- potent

## Derived Forms
- inefficaciously
- inefficaciousness

## Related Forms
- efficacious
- efficacy
- effect
- efficient

## Roots and Affixes
- Root: efficax
- Root: facere

## Etymology
From in- ('not') + efficacious, from Latin efficax ('effective'), from efficere ('to accomplish'), from ex- ('out') + facere ('to do, make').

## AI Etymology
Inefficacious comes from in- ('not') + efficacious, from Latin efficax ('effective'), from efficere ('to accomplish'), from ex- ('out') + facere ('to do, make'). The etymological trail includes Latin efficax and Latin facere. As an adjective, inefficacious means failing to produce the intended effect; ineffective. The same family is visible in derived forms such as inefficaciously and inefficaciousness and related forms such as efficacious, efficacy, effect, and efficient. Morphologically, the word is built from the elements named in its history, so the modern form preserves a visible compound, prefix, or suffix structure.

## Topics
- Cause, Change & Process
- Word Formation & Derivatives

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