ἐθελοπονία
From LSJ
ἑὰν δὲ προσποιούμενος ᾗ τὰ μαθήματά πως ἀπείρως προβάλλων, οὐκ ἔστιν αἰτίας ἔξω → But should one profess knowledge as he puts forward something in an inexperienced way, he is not without blame (Pappus 3.1.30.31f.)
German (Pape)
[Seite 718] ἡ, Liebe zur Arbeit, Arbeitsamkeit, Xen. Oec. 21, 6, l. d.