fossa

IPA/ˈfɒs.ə/
IPA/ˈfɑː.sə/

fossa — noun

  • fossasingular
  • fossasplural

1. a natural dip, pit, or groove in the body, most often found in a bone

1.nounC1
Definition

a natural dip, pit, or groove in the body, most often found in a bone

Example

Dr. Okafor pointed to a small fossa on the patient's hip X-ray.

collocation: small fossa on [bone]

The anatomy textbook labelled the fossa just below the shoulder blade.

Common collocations
  • iliac fossa
  • cranial fossa
  • glenoid fossa
  • temporal fossa
  • deep fossa
  • shallow fossa
Synonyms
  • depression

    more general; used for any sunken area on a surface, not only in anatomy

  • cavity

    implies a fully enclosed hollow space with walls, like the nasal cavity

  • groove

    long and narrow, like a channel; a fossa can be rounder or wider

  • pit

    sharper and deeper, like a small crater; more everyday than fossa

Antonyms
  • protrusion

    something that sticks out rather than sinking in

  • ridge

    a raised line along a bone, opposite of a groove-like fossa

Usage Note

Technical medical term. Never used to describe everyday holes, hollows, or pits outside anatomical contexts.

Common Mistakes

The child dug a fossa in the sand.
The child dug a hollow in the sand.
fossa is a medical term for a natural depression in the body, not a hole you make in the ground.

2. a meat-eating mammal from Madagascar that looks somewhat like a cat, with a slim

2.nounC1
Definition

a meat-eating mammal from Madagascar that looks somewhat like a cat, with a slim body, a long tail, and fur that is usually reddish-brown or black

Example

Yuki spotted a fossa slinking through the trees in a Madagascar nature reserve.

fossa + present participle for action

The zoo's new fossa drew crowds with its long tail and quick movements.

collocation: zoo's fossa

Common collocations
  • fossa habitat
  • male fossa
  • female fossa
  • fossa population

Usage Note

This animal lives only on the island of Madagascar and is not found in the wild anywhere else.

Common Mistakes

We saw a fossa in the Amazon rainforest.
We saw a fossa in a Madagascar nature reserve.
fossas are native only to Madagascar, not to South America.

Word family

  • fossular
    adjectiveC2

Synonym discussion

Sense: noun/1

All four words describe a sunken area, but they differ in context and precision. Depression is the most general and formal — doctors use it for any inward curve on a bone or organ surface. Cavity implies a fully enclosed empty space with walls, like the nasal cavity. Hollow is the most everyday word and suggests a shallow, scooped-out area — you would say a hollow in a tree, not a fossa. Pit is sharper and deeper, like a small crater — the pit of the stomach. Fossa sits between depression and hollow: it is a natural anatomical groove or dip, shallow and open on one side, never a fully enclosed cavity. A doctor examining an X-ray might note a fossa on the femur; a hiker resting against an old oak might lean into a hollow at the base of the trunk.

depression ↗cavity ↗hollow ↗pit ↗

Etymology

LatinMedical LatinEnglish

From Latin fossa ('ditch, trench'), from the past participle of fodere ('to dig'). The anatomical sense entered English in the 17th century through medical Latin, where it was used to name the natural hollows and grooves observed on bones and organs. The animal was named by 19th-century naturalists, likely adapting the Malagasy word fosa, though the exact path of borrowing is not fully settled.