aa
nounUK /ˈɑː.ɑː/
US /ˈɑː.ɑː/
Aa is a type of rough, bumpy lava rock.
The volcano left a field of sharp aa across the valley.
OTHER MEANINGS
2. A very young child; a baby.
The nurse checked on the aa sleeping in the crib.
3. A small cup or measure used in old medicine.
The apothecary poured the powder into an aa.
4. A river in northern France.
The aa flows into the sea near Gravelines.