nautical To issue and partake in an extra ration of alcoholic spirits, especially rum or grog, amongst members of crew aboard a sea vessel. (The mainbrace, also spelled "main brace," is a brace attached to the main yard on sailing ships. "Splicing the mainbrace" was originally the very difficult job of repairing this brace, one which earned the repairman an extra ration of spirits; eventually, this euphemistic secondary meaning became the primary one.) As part of the celebrations for her Diamond Jubilee, the Queen gave the order to all in the Royal Navy to splice the mainbrace as a gesture of good cheer.