porous

If something is full of tiny holes or openings, you can describe it as porous. A sponge is porous, and if the border between countries is open for anyone to cross easily, it too can be called porous.

You can see the word pore — meaning "a tiny opening" — in porous. When potters make a mug, they use special glazes to seal the porous clay, which otherwise would absorb the liquid you put in the mug. This meaning has expanded so porous can describe any barrier that allows easy passage in and out, like the porous border between two countries that allows residents to move easily between them.

Definitions of porous
1

adj full of pores or vessels or holes

Synonyms:
poriferous
porose
forming a continuous series of pores
Antonyms:
nonporous
not porous; especially not having vessels that appear as pores

adj allowing passage in and out

“our unfenced and largely unpoliced border inevitably has been very porous
Synonyms:
holey
leaky
permitting the unwanted passage of fluids or gases

adj able to absorb fluids

“the partly porous walls of our digestive system”
“compacting the soil to make it less porous
Synonyms:
permeable
allowing fluids or gases to pass or diffuse through

Sign up, it's free!

Whether you're a student, an educator, or a life-long learner, Vocabulary.com can put you on the path to systematic vocabulary improvement.