English Reference

Phrasal verb

clog up

Definition

phrasal verb. to block a pipe, road, or system so that things cannot flow through it. You use this when hair blocks a drain or too many files slow down your computer.

phrasal verb. to obstruct a channel, conduit, or system through the accumulation of material. This phrasal verb is frequently used in both literal and figurative contexts.

Examples

“Too much fat can clog up your arteries.”

“The heavy snowfall started to clog up the main roads, making it impossible for buses to finish their routes.”

“Administrative bureaucracy tends to clog up the system, preventing essential resources from reaching the frontline workers who need them most during a national crisis.”

Examples

simple

“Too much fat can clog up your arteries.”

contextual

“The heavy snowfall started to clog up the main roads, making it impossible for buses to finish their routes.”

complex

“Administrative bureaucracy tends to clog up the system, preventing essential resources from reaching the frontline workers who need them most during a national crisis.”

Usage

Often used with 'with' to indicate the substance causing the blockage.

Teaching tip

Contrast with 'block' and 'congest'; 'clog up' often implies a messy or gradual accumulation of waste or unwanted items.

Pitfall

The pipe is clogged up of dirt.

The pipe is clogged up with dirt.

Use the preposition 'with' to name the substance causing the blockage.

Phrasal verb

Particles

up

Separability

optional

Pattern

clog + up + object

Synonyms

blockjamobstructcongestplug

Antonyms

clearunblockopen

Grammar

Phrasal verbs (introduction)

This entry

Exam level
CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B2 FirstIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.5.5–6.5TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 4.0–4.572–94TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.785–944
Level
B2 · Upper Intermediate
Updated

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