semipermeable

adjective

semi·​per·​me·​able ˌse-mē-ˈpər-mē-ə-bəl 

ˌse-ˌmī-, 

-mi-

: partially but not freely or wholly permeable

specifically : permeable to some usually small molecules but not to other usually larger particles

a semipermeable membrane

semipermeability

ˌse-mē-ˌpər-mē-ə-ˈbi-lə-tē 

ˌse-ˌmī-, 

-mi-

noun

Examples of semipermeable in a Sentence

Recent Examples on the Web

The science behind this is based on the fact that eggshells are semipermeable, which means air can get through. — Michelle Darrisaw, Southern Living, 10 June 2026

For consumers, the best choice is a reverse osmosis system, which forces water through a semipermeable membrane that captures up to 99% of contaminants, Jones said. — Sandee Lamotte, CNN Money, 23 Apr. 2026

The electrochemical process separates out lithium by passing it through three compartments separated by semipermeable barriers. — IEEE Spectrum, 26 Feb. 2026

Nowhere seems to drift through this as through a semipermeable membrane. — David Searcy, Harpers Magazine, 30 Dec. 2025

Word History

First Known Use

1888, in the meaning defined above

Rhymes for semipermeable

• permeable
• impermeable

Kids Definition

semipermeable

adjective

semi·​per·​me·​able ˌsem-i-ˈpər-mē-ə-bəl 

ˌsem-ˌī-

: partially but not freely or entirely permeable

especially : permeable to some usually small molecules but not to other usually larger particles

semipermeability

-ˌpər-mē-ə-ˈbil-ət-ē 

noun

Medical Definition

semipermeable

adjective

semi·​per·​me·​able ˌsem-i-ˈpər-mē-ə-bəl, ˌsem-ˌī- 

: partially but not freely or wholly permeable

specifically : permeable to some usually small molecules but not to other usually larger particles

a semipermeable membrane

semipermeability

-ˌpər-mē-ə-ˈbil-ət-ē 

noun

plural semipermeabilities