adj. When "assy" (or even "asshatty") can't quite cover the magnitude of the assitude.
Real citation: "Members of a peaceful international community can respect each other's spacefaring attempts (though individual members may be quite assitudinous towards other as-of-not yet members)."
Made-up citation: "Last week, while canceling a date, I called her the wrong name. Yes, I am an assitudinous man."