Today we’re digging into the commonest meanings of another pair of potentially confusable Spanish nouns. These are fosa (feminine) and foso (masculine).
The two words have rather similar meanings in that they both refer to pit- or trench-like spaces.
However, the feminine word fosa often has some rather grave associations that it shares with tumba and sepultura. Let’s start with that then.
You can listen to how fosa (feminine) is pronounced here:

Una fosa is often a grave (or burial pit), a simple hole in the ground into which one body (or more) is placed before being covered with soil:
Fue enterrado en una fosa común.
He was buried in a common grave.
No han podido identificar 500 cuerpos enterrados en seis fosas comunes.
They haven’t been able to identify 500 bodies buried in six mass graves.
Cavó una fosa suficiente para enterrar el cadáver.
He dug a big enough pit to bury the body in.
As in English this sense of fosa is sometimes used figuratively:
Ha cavado su propia fosa.
He’s dug his own grave.
Moving on from its more chilling uses, una fosa may be used of pit-like places where waste is left:
Había caído en una fosa séptica.
He had fallen in a septic tank.
Una fosa can also be a hollow space in the body – a (bodily) cavity:
En el interior de nuestras fosas nasales se encuentran unos diez millones de células olfativas.
There are some ten million olfactory cells in our nasal cavities.
Finally, fosa is used of ocean trenches:
la llamada fosa atlántica
the so-called Atlantic trench
Let’s bury fosa (along with tumba and sepultura – other words for grave) and move on to the masculine foso, whose pronunciation can be heard here:

Foso does not have the grim associations of its feminine counterpart. Un foso can be a hole, pit, trench or ditch depending on shape and size among other things:
Trabajaba en el interior de un foso de cuatro metros de profundidad.
She was working inside a hole/pit/trench four metres deep.
Me caí al foso de los músicos.
I fell into the orchestra pit.
Ha sido rescatado del foso de los leones.
He was rescued from the lion pit.
el foso utilizado habitualmente en las tareas de reparación del vehículo
the (inspection) pit normally used for vehicle repair work
Un foso can also be a defensive trench around an old castle or town – a moat:
El foso medieval se utilizó también como vertedero.
The medieval moat was also used as a tip or dump.
Se pueden visitar las torres y el foso del castillo medieval del siglo XII.
The towers and moat of the 12th-century medieval castle can be visited.
Un foso is also sometimes used figuratively to mean gulf:
La distancia entre los ciudadanos ricos y los ciudadanos pobres se hace más grande y el foso entre países ricos y países pobres se hace más profundo.
The distance between rich and poor citizens is getting wider and the gulf between rich and poor countries deeper.
QUIZ TIME
In the following, can you spot an English term that shares the same Latin root as foso and fosa?
Though a badger’s eyesight is poor (as you would expect from a nocturnal and fossorial animal), they can detect movement.
These little fossorial animals (moles) rely on a moist, diggable soil to access their main diet of earthworms, centipedes and insect larvae.
Yes, the word is fossorial, meaning burrowing. It is derived from a Latin word for to dig.
Join us again next week as we continue unearthing the differences between similar-looking Spanish nouns.