Sets of points, in math (4)
I believe the answer is:
loci
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sets of points in math</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for loci that I've seen before include "Particular positions" , "Particular places" , "locations" , "Points where something occurs; coil (anag.)" , "sites" .)