related: Kippa in Torah?
The talmud in Kiddush 31a relates that
רב הונא בריה דרב יהושע לא מסגי ארבע אמות בגילוי הראש "Rav Huna, son of Rav Yehoshua, would not walk four cubits with an uncovered head".
The talmud uses the word misgei which is presented (switching from, I'm guessing, the Aramaic) by the Rif as שיהלך (and understood as that by the Steinzaltz). The Aramaic itself, as evidenced by its use in the targum, seems to refer to an abundance or something not about "going."
מסגי m. (סגי I) multitude. Targ. Y. Deut. X, 22. Targ. O. Gen. XXX, 80; a. e. --Targ. Is. V, 24, v. מסגן.]-V. סגיIII.
I'm not sure what exact word is being used (if it isn't the Aramaic) or how the word is actually used in this context -- it seems weird that a statement in Hebrew would be punctuated by an Aramaic word, especially when there are Hebrew ones readily available. But because I don't fully understand that word, I don't understand its scope and limitations.
Would this rabbi only apply this head covering to "going" which is walking? Would riding on a horse be the same "going"? I know that some people, using a more modern Hebrew, distinguish between h-l-ch (go, implying walking) and n-s-a (travel, implying another form of movement).
Would someone sitting on a boat or an airplane, who is certainly traveling but not walking, still be "required" (acknowledging the notion that this is a custom, so I'm hesitant to use the absolute language of "obligated") to have his head covered?
Are there responsa which deal with this and clarify what "misgei" applies to?