Mention casually' is an expression used to describe a casual way of bringing up a topic or idea. ALLUDE, which has 6 letters, is a verb meaning to suggest or hint at something without directly saying it. DROP, with 4 letters, is a verb meaning to say something quickly and casually. Slipin, also with 6 letters, is a verb meaning to bring up a topic in a subtle or indirect way. Together, these three words can be used to describe the act of mentioning something casually.