The word gymnastics derives from the common Greek adjective γυμνός (gymnos) meaning "naked", by way of the related verb γυμνάζω (gymnazo), whose meaning is to train naked", "train in gymnastic exercise", generally "to train, to exercise". The verb had this meaning, because athletes in ancient times exercised and competed without clothing. It came into use in the 1570s, from Latin gymnasticus, from Greek gymnastikos "fond of or skilled in bodily exercise," from gymnazein "to exercise or train" (see gymnasium).

Answer this question, if possible (if impossible, reply "unanswerable"): What does the  verb gymnazo mean?
to train naked", "train in gymnastic exercise", generally "to train, to exercise"