At a first glance this seems to be a plural feminine. Also feminine noun מְצִיעוּת, mediation, is found in dictionaries.
What then? Since two feminine nouns come before our word... is it not more logical to think that our word is a feminine plural?
But then... which is the singular?
Here is another case to realize the usefulness of Oham. If we consider the possibility that this is a word fitting a pattern PIS-d... let's take a look at Index PIS-d. And fix our sight to the left part of the drawing, the hasar haniqud.
After an attentive looking, we see that only PIS-d484, epigraph 1, is the answer we're seeking for.
Indeed, root יצ"ע is used in the Hiph'il with meaning to propose, to offer.
So we get (females) who propose, who offer.