The poem describes the Owl and the Pussy-cat setting sail in a pea-green boat, and includes the line:
"They dined on mince and slices of quince,
Which they ate with a runcible spoon."
The word "runcible" is made-up, with no real definition. It's simply meant to sound quirky and funny.
What it *might* be:
* A spoon with a unique, unusual shape: The poem itself doesn't describe what a runcible spoon looks like, leaving it open to interpretation. Some have suggested it might be a spoon with a handle that curves back towards the bowl, or a spoon with a serrated edge.
* A metaphorical utensil: Perhaps the runcible spoon represents something other than an actual utensil. It could symbolize the absurdity of the situation, the whimsical nature of the journey, or even the Owl and the Pussy-cat's unusual appetites.
Ultimately, the "runcible spoon" is just a silly and charming element of Edward Lear's poem, meant to add to its nonsensical charm. It's a great example of Lear's talent for creating humorous and imaginative wordplay.