This is the 4260th most frequent German word.
durchschnittliche
"Durchschnittliche" means "average" or "ordinary" in English.
Here, 'durchschnittliche' modifies the noun 'Temperatur', describing it as the mean or average temperature value.
Die durchschnittliche Temperatur beträgt im Sommer 25 Grad.
The average temperature in summer is 25 degrees.
In this sentence, 'durchschnittliche' qualifies the noun 'Leistung', indicating mediocrity or a standard level of performance.
Er hat eine durchschnittliche Leistung im Training gezeigt.
He showed an average performance in the training.
Here, 'durchschnittlich' is used in an adjectival form to describe 'Kunst', referring to it as being of standard quality or typical notability.