A weevil is a type of beetle from the Curculionoidea superfamily. Weevils can be easily recognised by the long rostrum or snout, an elongated part of the front portion of the head. Quite often rhynch (meaning nose) is part of the species or generic name. The snout is sometimes mistaken as the piercing-sucking proboscis, however, the tip of the rostrum bears tiny little chewing mouthparts. The rostrum can be of considerable length, sometimes as long as the body of the weevil and is housed in an abdominal groove during rest. The antennae are usually clubbed and mostly elbowed.

The weevils general body form is variable, some species are quite long and slender as in the closely related Brentidae whereas others are small, stout and nearly spherical. The legs can be quite long and well developed for running and can be retracted in many species against the very hard body. Upon disturbance weevils usually drop and feign death. The apod weevil larvae in general lack legs and are of white or pale creamy colour. Most Curculionidae larvae are cryptic miners or borers that feed within plant tissue.They are usually small, less than 6 mm , and herbivorous. Over 60,000 species are in several families, mostly in the family Curculionidae Some other beetles, although not closely related, bear the name "weevil", such as the biscuit weevil (Stegobium paniceum), which belongs to the family Anobiidae.

Many weevils are considered pests because of their ability to damage and kill crops, but others are used for biological control of invasive plants. The grain or wheat weevil (Sitophilus granarius) damages stored grain. The boll weevil (Anthonomus grandis) attacks cotton crops. It lays its eggs inside cotton bolls, and the larvae eat their way out.

Almost all weevils are associated with woody plants and all parts are fed upon: wood, cambium, roots, leaves, seeds, fruits, flowers and terminal shoots. Therefore weevils are severe pests of agricultural and forestry crops as well as stored products. There is hardly any plant that cannot be infested by at least one weevil species.

One species of weevil, Austroplatypus incompertus, exhibits eusociality, one of the few insects outside the Hymenoptera and the Isoptera to do so.

Because so many species exist in such diversity, the higher classification of weevils is in a state of flux. They are generally divided into two major divisions, the Orthoceri or primitive weevils, and the Gonatoceri or true weevils . E. C. Zimmerman proposed a third division, the Heteromorphi, for several intermediate forms. Primitive weevils are distinguished by having straight antennae, while true weevils have elbowed antennae. The elbow occurs at the end of the scape in true weevils, and the scape is usually much longer than the other antennal segments. Some exceptions occur. Nanophyini are primitive weevils (with very long trochanters), but have long scapes and geniculate antennae. From the true weevils, Gonipterinae and Ramphus have short scapes and little or no elbow.

The most recent classification system to family level was provided by Kuschel, with updates from Marvaldi et al., and was achieved using phylogenetic analyses. The accepted families are the primitive weevils, Anthribidae, Attelabidae, Belidae, Brentidae, Caridae, and Nemonychidae, and the true weevils Curculionidae. Most other weevil families were demoted to subfamilies or tribes. Weevil species radiation was shown to follow steps in plant evolution upon which the weevils feed; they can vary in color from black to light brown.

The Curculionidae comprise the family of the true weevils (or snout beetles). It is one the largest animal families, with 5,489 genera and 86,100 species described worldwide.

It also includes the bark beetles as subfamily Scolytinae, which are modified in shape in accordance with their wood-boring lifestyle. They do not much resemble other weevils, so they were traditionally considered a distinct family, Scolytidae. The family also includes the ambrosia beetles, of which the present-day subfamily Platypodinae was formerly considered the distinct family Platypodidae.

They are recognized by their distinctive long snouts and geniculate antennae with small clubs; beyond that, curculionids have considerable diversity of form and size, with adult lengths ranging from 1 to 40 mm .

Weevils are almost entirely plant feeders, and most species are associated with a narrow range of hosts, in many cases only living on a single species. With so many species to classify and over 400 genera, the taxonomy of this family is quite complicated, and authors disagree on the number and placement of various subfamilies, tribes, and subtribes.