mostly

mostly — adverb

1. used to say that something is true about the largest part of a group, amount, or

1.adverbB1
Definition

used to say that something is true about the largest part of a group, amount, or situation, but not necessarily all of it

Example

The children in this class are mostly seven years old.

mostly after 'be' with complement

Anya mostly takes the bus when she goes into the city.

mostly before main verb

Common collocations
  • are mostly
  • mostly about
  • mostly because
  • mostly used
  • mostly made up of
Synonyms
  • mainly

    the closest synonym; interchangeable in almost all contexts

  • largely

    slightly more formal; emphasises scale rather than simple majority

  • chiefly

    more formal; often used to list the most important reasons or components

  • for the most part

    a longer, slightly more conversational phrase covering the same meaning

Antonyms
  • slightly

    opposite on a scale of degree — 'mostly' implies a large part, 'slightly' implies a small part

  • barely

    emphasises the smallest possible amount, the opposite of 'mostly'

Grammar Patterns

mostly before main verb

mostly after 'be'

mostly at start of clause for contrast

Usage Note

Unlike 'almost' or 'most of', 'mostly' refers to proportion or frequency, not near-completeness. It typically appears before the main verb but after the verb 'be'. In formal writing, 'mostly' is common; 'chiefly' or 'largely' are slightly more formal alternatives.

Common Mistakes

Mostly everyone agreed with the plan.
Almost everyone agreed with the plan.
'mostly' describes proportion of a thing, not near-completeness; use 'almost' before 'everyone/everything'.
She spends mostly her free time reading.
She spends most of her free time reading.
'mostly' is an adverb and cannot replace 'most of' before a noun phrase.

Word family

Synonym discussion

Sense: adverb/1

All four describe the dominant part of a situation, but they differ in formality and nuance. 'Mainly' is the closest and most neutral equivalent of 'mostly' — they are interchangeable in nearly all everyday contexts. 'Largely' adds a sense of scale or extent: 'The project was largely successful' sounds more about the overall magnitude than a simple count of parts. 'Chiefly' carries a more formal, almost literary tone and often introduces the single most important element in a list: 'The festival is chiefly a celebration of local music.' 'For the most part' is a longer, slightly more conversational phrase that often implies some exceptions: 'For the most part, the weather was good' leaves room for a few bad days. In short: use 'mainly' or 'mostly' for neutral everyday speech, 'largely' for emphasis on extent, 'chiefly' in formal lists, and 'for the most part' when you want to acknowledge exceptions casually.

mainly ↗largely ↗chieflyfor the most part ↗

Common collocations

Adverbs

  • almost mostly
  • mostly just
  • mostly only

Phrases

Etymology

Old EnglishMiddle EnglishEnglish

Combines 'most' (from Old English 'mǣst', meaning 'greatest in amount or degree') with the adverbial suffix '-ly'. First recorded in the 16th century, it gradually developed from meaning 'in the highest degree' to its modern sense of 'for the most part' or 'mainly'.