subarachnoid

adjective

sub·​arach·​noid ˌsəb-ə-ˈrak-ˌnȯid 

variants or less commonly subarachnoidal

ˌsəb-ə-rak-ˈnȯi-dᵊl 

: of, relating to, occurring, or situated under the arachnoid membrane

subarachnoid hemorrhage

Examples of subarachnoid in a Sentence

Recent Examples on the Web

In February 2011, shortly after filming the first season of Game of Thrones, Clarke experienced a subarachnoid hemorrhage and underwent a minimally invasive emergency surgery. — Chanel Vargas, InStyle, 4 June 2026

In this case of a 1-month-old from Alabama, the autopsy found that the baby had suffered subdural and subarachnoid hemorrhage, which are types of bleeds that occur in different areas immediately on top of the brain. — Duaa Eldeib, ProPublica, 18 May 2026

The child was taken to the hospital for medical treatment and is currently in the pediatric intensive care unit with bilateral skull fractures and subdural and subarachnoid hemorrhages, according to the arrest citation. — Caroline Neal, Louisville Courier Journal, 4 Sep. 2025

The study showed that COVID patients had an 80 percent higher risk of subarachnoid hemorrhage compared to those without it. — Alyce Collins, MSNBC Newsweek, 15 Aug. 2025

The leaking brain aneurysm led to a subarachnoid hemorrhage, or bleeding in the space between the brain and a thin membrane that covers and protects it. — Robert Glatter, Forbes.com, 20 June 2025

Word History

First Known Use

1843, in the meaning defined above

Rhymes for subarachnoid

• albuminoid
• arytenoid
• cannabinoid
• carotenoid
• epidermoid
• epithelioid
• meteoroid
• paraboloid
• underemployed
• adenoid
• alkaloid
• amoeboid

Medical Definition

subarachnoid

adjective

sub·​arach·​noid ˌsəb-ə-ˈrak-ˌnȯid 

variants also subarachnoidal

-rak-ˈnȯid-ᵊl 

1

: situated or occurring under the arachnoid membrane

subarachnoid hemorrhage

2

: of, relating to, or involving the subarachnoid space and the fluid within it

subarachnoid meningitis