emphasis You can use mammoth to emphasize that a task or change is very large and needs a lot of effort to achieve. the mammoth task of relocating the library = massive
A mammoth was an animal like an elephant, with very long tusks and long hair, that lived a long time ago but no longer exists. extremely large = enormous, gigantic gigantic. an animal like a large hairy elephant that lived on Earth thousands of years ago. Any of several species (genus Mammuthus) of extinct elephants whose fossils have been found in Pleistocene deposits (beginning 1.8 million years ago) on every continent except Australia and South America. The woolly, Northern, or Siberian mammoth (M. primigenius) is the best-known species because the Siberian permafrost preserved numerous carcasses intact. Most species were about the size of modern elephants; some were much smaller. The North American imperial mammoth (M. imperator) grew to a shoulder height of 14 ft (4 m). Many species had a short, woolly undercoat and a long, coarse outer coat. Mammoths had a high, domelike skull and small ears. Their long, downward-pointing tusks sometimes curved over each other. Cave paintings show them traveling in herds. Mammoths survived until about 10,000 years ago; hunting by humans may have been a cause of their extinction. See also mastodon
so exceedingly large or extensive as to suggest a giant or mammoth; "a gigantic redwood"; "gigantic disappointment"; "a mammoth ship"; "a mammoth multinational corporation"