Of all the collective nouns for toads, “lump” might be the most visually accurate. Toads are stockier and less streamlined than frogs, with short legs built for hopping short distances rather than leaping, and when several of them settle in the same spot, the result really does look like a small, warty pile — a lump, in the most literal sense.
The exact origin of the term isn’t documented in detail, but like many of the toad-specific collective nouns, it likely grew out of plain observation rather than any formal tradition. Toads are homebodies. Once they find a reliable shelter — a damp spot under a porch, a hollow beneath a rock — they tend to stay close to it and to each other, especially during the day when they’re avoiding heat and predators.
This clustering behavior isn’t purely social, either. Staying grouped and low to the ground helps toads conserve moisture, which matters more for them than it might seem. Despite their drier, bumpier skin, toads still lose water through it and rely on damp, sheltered microhabitats to avoid drying out.
Example: “A lump of toads had claimed the shady gap under the garden shed for the summer.”
Related: Collective Nouns for Amphibians · What Is a Group of Toads Called?