This is the 13781st most frequent German word.
erfolgreichste
"Most successful."
Here, 'erfolgreichste' is used as an adjectival superlative, modifying 'Methode,' describing it as the most successful one.
Die erfolgreichste Methode, Deutsch zu lernen, ist regelmäßiges Üben.
The most successful method to learn German is regular practice.
In this sentence, 'erfolgreichste' is applied as a superlative adjective attached to 'Spieler,' indicating the player with the highest level of success in the club's history.
Er ist der erfolgreichste Spieler in der Geschichte des Vereins.
He is the most successful player in the club's history.
This usage of 'erfolgreichste' serves as a superlative adjective describing 'Wissenschaftlerin,' portraying that individual as the most successful among scientists in that context.