What does caterpillar mean?
A caterpillar is the larval stage of a butterfly or moth: a soft-bodied, elongated insect with a distinct head and several pairs of legs, known for feeding intensively on leaves and other plant matter. After hatching from an egg, the caterpillar grows rapidly, often shedding its skin several times as it increases dramatically in size, before entering the pupal stage inside a chrysalis and ultimately emerging as a winged adult. Beyond entomology, the word has taken on a mechanical sense: 'caterpillar tracks' or 'caterpillar treads' describe the continuous belt-like tracks on tanks and tractors, named because their undulating motion resembles the insect's gait — an association cemented by the Caterpillar brand of heavy machinery. The word carries no strong emotional connotation and is equally at home in a child's picture book, a gardener's complaint, or a biology textbook. Its transformation into a butterfly makes it a lasting cultural symbol of change and growth.
nounThe larval stage of a butterfly or moth: an elongated, segmented creature with a soft body and several pairs of legs that feeds voraciously on plants before metamorphosing. The word can also refer informally to a tracked vehicle with caterpillar-like treads.
- The larval stage of a butterfly or moth.
- Informally or attributively, a tracked vehicle with continuous treads resembling a caterpillar's legs (as in 'caterpillar tractor').
"A monarch caterpillar devoured milkweed leaves at an astonishing rate before spinning its chrysalis."
"The children watched a fuzzy caterpillar inch along the garden fence."
"The old bulldozer's caterpillar tracks churned through the mud with ease."
Standard plural; simply add -s. Used both literally for multiple larvae and figuratively for groups.
"Tent caterpillars stripped the orchard's branches bare by midsummer."
Before it becomes a butterfly, a caterpillar eats so much that it can increase its body mass a thousandfold in just a few weeks.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of caterpillar
The word 'caterpillar' entered English in the late Middle Ages via Old North French 'caterpilose', which itself traces back to Late Latin roots meaning 'shaggy cat' — combining 'catta' (cat) with 'pilosus' (hairy), from Latin 'pilus' meaning hair. This origin reflects the hairy or bristled appearance many caterpillars display. Related English words drawing on the same Latin 'pilus' include 'pile' (a fabric with a raised, hairy surface) and 'depilatory'.
How caterpillar is actually used
The word is common and neutral in register, used freely in both everyday speech and scientific writing about lepidoptery. In American English it is often shortened colloquially to 'cat', though this is informal. When used attributively ('caterpillar tracks'), it evokes the machine brand Caterpillar Inc., which popularized the tracked-vehicle association.
Easily confused with caterpillar
A cocoon is the protective casing a caterpillar spins around itself before pupating, whereas the caterpillar is the larval insect itself.
A grub is typically the larva of a beetle or other insect, while a caterpillar specifically refers to the larva of butterflies and moths.