This is the 4505th most frequent German word.
mittlere
"Mittlere" means "middle" or "intermediate" in English.
Here, 'mittlere' is used as an adjective to describe the child who is positioned in the middle in terms of birth order or age.
Das mittlere Kind mag gerne Schokolade.
The middle child likes chocolate.
In this sentence, 'mittlere' describes the option that is in a middle position among a set of choices.
Die mittlere Option ist die praktikabelste.
The middle option is the most practical.
Here, 'mittlerem' describes the level of traffic, indicating it is moderate—not too high or too low.