Wouldn't it be better to put in the category "Lieder" only those songs, which are "...arranged for a single singer and piano", as it is mentioned in the description? Especially the a-capella songs for choir (male choir or mixed choir) I would prefer to be described as "part songs", even though this term is not a german one. ;-)
The german word "Lied" (Plural "Lieder") has two different meanings: In colloquial german it is used for every song or piece of music, most times for music pieces with text (Horrible, but I heard from a pupil: The Lied "Moldau" from Smetana !!!). Often used are combinations like "Weihnachtslied" (Christmas carol), "Studentenlied" (students song), "Kinderlied" (children's song), and so on. The special meaning (like a technical term) of "Lied" is the one mentioned above. I think that the term "Lied" is used in many languages in this way. As a musician I would not look for songs for male choir (for example Schubert's "Die Nacht", "Im Abendrot", or Schumann's "Die Rose stand im Tau") in the category "Lieder". I would be glad to read some other opinions (and, please, be merciful with my bad English!).