This is the 4782nd most frequent German word.
aa
"Aa" is a dialectal German word meaning a small stream or river.
Here, use 'Aa' referring to 'lava' in geological terms as a noun.
Aa ist ein Ausdruck im Deutschen.
Aa is an expression in German.
Here, 'Aa' is used as an exclamation or vocalization, informally used by children.
Das Kind sagte 'Aa', als es spielen wollte.
The child said 'Aa' when it wanted to play.
Here, 'Aa' is used as a scientific term describing a type of volcanic lava.