Cystic swelling in the floor of the mouth Bluish-purple in colour............... Most likely a Ranula (painless)
Ranula Ranula is mucocele that occur in the floor of the mouth and usually involve the major salivary glands. Specifically, the ranula originates in the body of the sublingual gland, in the ducts of Rivini of the sublingual gland, in the Wharton duct of the submandibular gland, and, infrequently from the minor salivary glands at this location