What?
First of all, you ask, "what is Similitude?"
Well, the Computer dictionary definition of Similitude is:
" similitude |siˈmiləˌt(y)oōd| noun
the quality or state of being similar to something. ...
• … a comparison between two things.
• ... a person or thing resembling someone or something else.
ORIGIN late Middle English : from Old French, from Latin similitudo, from similis ‘like.’ "
So, bottom line -- 'similitude' is something being like or resembling something.
Your next question, probably is: "so what does it mean when it says 'similitude of God'?
This short article answers that question and gives important information that everyone needs to know.