Expletives
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">expletives</span>' is the definition.<br/ ><span class="explanation-format__explanation">('oath' can be a synonym of 'expletive')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for oaths that I've seen before include "Profane expressions" , "Imprecations" , "professions of loyalty" , "Expletives" , "truths may be established by them" .)