Passage: It bore the traditional names Hadar and Agena. Hadar comes from the Arabic حضار (the root's meaning is "to be present" or "on the ground" or "settled, civilized area"), while the name Agena  may ultimately be derived from the Latin genua, meaning "knees". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Hadar for the star β Centauri Aa on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.The Chinese name for the star is 马腹一 (Mandarin: mǎ fù yī, "the First Star of the Horse's Abdomen").The indigenous Boorong people of what is now northwestern Victoria, Australia named it as Bermbermgle (together with α Centauri), two brothers who were noted for their courage and destructiveness, and who spear and kill Tchingal, "The Emu" (Coalsack Nebula). The two brothers in Wotjobaluk people is Bram-bram-bult.

Question: What does knees mean in Latin?
genua