This is the 3872nd most frequent French word.
aigu
Sharp; high-pitched; acute.
Here, 'aigu' is used to describe the sharpness or high-pitched quality of the cry.
Le cri de l'oiseau était aigu.
The bird's cry was sharp.
In this sentence, 'aigu' refers to the acute nature of an angle in geometry.
Cet angle est très aigu.
This angle is very acute.
'Aigu' in this instance signifies clarity and precision in someone’s ability to observe details.