pm

pm — abbreviation

1. written abbreviation for 'post meridiem' in Latin, meaning after noon; used with

1.abbreviationA1
Definition

written abbreviation for 'post meridiem' in Latin, meaning after noon; used with times from 12:00 in the middle of the day to 11:59 at night, to show that you are talking about the afternoon, evening, or night rather than the morning.

Example

Hugo's flight arrives at 10:15 pm tonight, so we can pick him up after dinner.

time notation: [hour] + pm

The library closes at 6 pm on Fridays during the summer holidays.

Antonyms
  • am

    used for times before noon (midnight to 11:59 in the morning)

Grammar Patterns

[number] + pm

Usage Note

In informal writing, 'p.m.' with dots or 'pm' without dots are both common. On schedules and digital clocks, 'PM' in capital letters is standard. The 12-hour clock system using am/pm is common in the US, Canada, Australia, and the UK, while many other countries use the 24-hour clock.

Common Mistakes

The store closes at 12pm.
The store closes at noon.' or 'The store closes at 12:00 pm.
12 pm is noon (not midnight); this is a common source of confusion. To be clear, use 'noon' or 'midnight' instead.

2. written abbreviation for 'prime minister', used as a title before a person's nam

2.abbreviationB1
Definition

written abbreviation for 'prime minister', used as a title before a person's name in newspapers, official documents, and captions.

Example

PM Tariq addressed the nation after the election results were announced.

title use: PM + [name]

The newspaper headline read: "PM Reema visits flood-affected areas."

Grammar Patterns

PM + [name]

the PM

Usage Note

This abbreviation sense is a title used directly before a name (e.g., PM Sunak). When talking about the position in ordinary speech or writing using articles ('the PM', 'a new PM'), use the noun sense instead — it follows normal noun grammar patterns.

3. written abbreviation for 'particulate matter'; extremely small pieces of dust, s

3.abbreviationC1
Definition

written abbreviation for 'particulate matter'; extremely small pieces of dust, soot, smoke, or liquid droplets floating in the air, especially when measuring air pollution.

Example

PM2.5 levels in Hanoi reached dangerous levels during the dry season.

followed by size number: PM2.5, PM10

The government issued a warning when PM concentrations exceeded the safety limit.

Common collocations
  • PM levels
  • PM concentration
  • PM index
  • PM2.5
  • PM10

Grammar Patterns

PM + [size number]

PM levels

Usage Note

PM is always followed by a number that indicates the size of the particles in micrometres. PM2.5 refers to particles smaller than 2.5 micrometres (the most dangerous for human health). PM10 refers to larger particles up to 10 micrometres.

4. written abbreviation for 'premium', used in financial and insurance contexts to

4.abbreviationB2
Definition

written abbreviation for 'premium', used in financial and insurance contexts to mean the regular payment made for an insurance policy, or an additional amount paid above the standard price.

Example

The monthly PM on Camila's health insurance went up by fifteen percent.

insurance context: PM on [policy]

Investors paid a PM of eight percent above the market price for those shares.

finance context: paid a PM of [amount]

Grammar Patterns

[amount] + PM

pay a PM

Usage Note

This abbreviation is most common in written financial documents and insurance statements. In everyday speech, 'premium' (the full word) is preferred. The meaning depends on context: insurance premium = regular payment; bond premium = extra amount above par value.

5. the chemical symbol for promethium, a radioactive metallic element with atomic n

5.abbreviationC2
Definition

the chemical symbol for promethium, a radioactive metallic element with atomic number 61 that belongs to the lanthanide series. It does not occur naturally in large amounts and is produced inside nuclear reactors.

Example

The element Pm is a radioactive metal that glows in the dark.

element Pm: scientific context

Scientists use Pm-147 to power small batteries for spacecraft and pacemakers.

Pm + isotope number: Pm-147

Grammar Patterns

Pm + [isotope number]

element + Pm

Usage Note

Pm is the official IUPAC symbol for promethium and is used in the periodic table and chemical formulas. In speech, it is pronounced as the full element name, not as 'P-M'.

pm — noun

Word family

  • promethium
    nounC2

Synonym discussion

Sense: abbreviation/1

The abbreviations 'am' and 'pm' are used with the 12-hour clock to divide the day: 'am' covers midnight to noon (00:00–11:59), and 'pm' covers noon to midnight (12:00–23:59). This system is standard in the US, Canada, the UK, Australia, and New Zealand, but many other countries use the 24-hour clock (e.g., 14:00 instead of 2:00 pm). A common point of confusion is 12:00 am (midnight) vs 12:00 pm (noon); to avoid ambiguity in schedules and invitations, use '12 noon' and '12 midnight' instead. Both 'am' and 'pm' can be written with or without dots (a.m./p.m. or am/pm), and in capital or lowercase letters.

am ↗pm ↗noon ↗midnight ↗

Common collocations

Nouns

  • pm slot
  • pm deadline
  • pm appointment

Phrases

  • am and pm
  • late pm
  • early pm

Prepositions

  • at + [time] + pm
  • by + [time] + pm
  • from + [time] + pm + to + [time]

Etymology

LatinEnglish

The abbreviation 'p.m.' comes from the Latin phrase 'post meridiem', meaning 'after midday'. This time-notation system was inherited from ancient Roman timekeeping and became standard in English through the adoption of the 12-hour clock. The other meanings of 'pm' are all modern initialisms from the 20th and 21st centuries: 'prime minister' (18th century but abbreviated form became common later), 'particulate matter' (1970s environmental science), 'premium' (financial abbreviation), 'project manager' (1980s business culture), and 'private message' (1990s internet forums). The chemical symbol 'Pm' for promethium was assigned by the International Union of Pure and Applied Chemistry (IUPAC) in the 1940s when the element was synthesized.