OS can look to the Type specifics... but, for
asymptotic flare
the term shows an engineering science background... asymptotic (from asymptote = literally, not intersecting ie something in the nature of a tangent) is a math buzzword and is what the flight path is doing as it curves from the climb to the cruise, approaching the cruise path progressively more gradually. Flare is an upside version of what you do during the landing or takeoff .. hence a fancy way of saying that you gently bunt over from the climb to adopt the cruise ....