porous

adjective

po·​rous ˈpȯr-əs 

1

a

: possessing or full of pores

b

: containing vessels

hardwood is porous

2

a

: permeable to fluids

b

: permeable to outside influences

3

: capable of being penetrated

porous national boundaries

porously adverb

porousness noun

Synonyms of porous

• penetrable
• permeable

Examples of porous in a Sentence

The country has a porous border.

a cleaner that should not be used on porous surfaces

Recent Examples on the Web

At the microscale, the team fabricated porous, sponge-like particles roughly 2 micrometres in diameter, significantly thinner than a human hair, and tuned their internal chemistry to maintain long-term stability in aqueous environments. —Bojan Stojkovski, Interesting Engineering, 26 Apr. 2026

Scott Dochterman grades the pick Baltimore addressed its porous pass rush (30 sacks last year) by signing Trey Hendrickson this offseason. —Matt Moret, New York Times, 25 Apr. 2026

The borders between them are always porous. —Fintan O’Toole, The New York Review of Books, 25 Apr. 2026

The filter of peer review, meant to weed out subpar science, tends to be more porous with special issues. —Anil Oza, STAT, 24 Apr. 2026

Word History

First Known Use

14th century, in the meaning defined at sense 1a

Phrases Containing porous

• diffuse-porous
• ring-porous

Rhymes for porous

• chloris
• chorus
• horus
• lores
• morrice
• morus
• orris
• porus
• torus
• authorise
• clitoris
• liquorice

Kids Definition

porous

adjective

po·​rous ˈpōr-əs 

ˈpȯr-

1

: full of pores

2

: capable of absorbing liquids

Medical Definition

porous

adjective

po·​rous ˈpōr-əs, ˈpȯr- 

1

: possessing or full of pores

porous bones

2

: permeable to fluids