Muggy (5)

I believe the answer is:
humid
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">muggy</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for humid that I've seen before include "Dank" , "Describes air that contains a great deal of water vapour" , "Muggy" , "Damp and warm" , "Sultry" .)