tireless

tireless — adjective

1. continuing to work with strong effort and energy for as long as needed, without

1.adjectiveB2
Definition

continuing to work with strong effort and energy for as long as needed, without becoming tired

Example

Ryan's tireless efforts helped the team finish the project ahead of schedule.

collocation: tireless efforts

Tunde was tireless in his work to help homeless families find housing.

be tireless in + [activity]

Common collocations
  • tireless efforts
  • tireless work
  • tireless dedication
  • tireless search
  • tireless in + [activity]
Synonyms
  • hardworking

    more common and general; does not emphasise the continuous energy aspect

  • untiring

    similar meaning; slightly less frequent but interchangeable in most contexts

  • indefatigable

    very formal register; C2-level synonym with the same core meaning

  • diligent

    focuses on careful, thorough effort rather than sustained energy

Antonyms
  • lazy

    opposite in terms of effort; informal

  • lethargic

    suggests a physical lack of energy or motivation

Usage Note

Frequently used in formal or written contexts to praise someone's admirable dedication. Can appear before a noun (a tireless worker) or after a linking verb (she was tireless).

Word family

Synonym discussion

Sense: adjective/1

Tireless and untiring are the closest pair — both describe someone who keeps working without showing fatigue, but untiring is slightly less common. Hardworking is a simpler, more everyday word that focuses on putting in effort but does not necessarily imply the continuous, energetic quality of tireless. Diligent shifts the emphasis to carefulness and thoroughness rather than sustained energy. Indefatigable is the most formal synonym, typical of literary or very formal writing. For example, you would call a nurse who works double shifts tireless, a student who checks every detail diligent, and a lifelong human-rights campaigner indefatigable.

hardworkinguntiring ↗diligentindefatigable

Common collocations

Nouns

Prepositions

Etymology

Old EnglishEnglish

Formed from the verb tire (meaning 'to become weary', from Old English teorian) and the suffix -less (meaning 'without'). The word has been used since the 1800s to describe people or actions that show no sign of getting tired.