The term is also written as bassinet or basinet.
The earliest versions of the bascinet, at the beginning of the 14th century, had no visors, and were worn underneath larger "great helms." After the initial clash of lances, the great helm was often discarded during fierce hand-to-hand combat, as it impeded breathing and vision. Thus, having a smaller helmet underneath was a real advantage. Small "nasals" were developed to protect the nose and part of the face after the great helm was discarded. By the middle of the 14th century, most knights discarded the great helm altogether in favor of a fully visored bascinet. The visor was often conical, giving the appearance of a muzzle or a beak. They were sometimes called "dog faced" (medievally known as a hounskull) or "pig faced" (a common but strictly modern term). The early versions sometimes had a neck defence of mail called a camail or aventail, while later versions (at the end of the 14th century) often protected the neck with a separate but attached plate assembly, the gorget. The aventail was attached to a leather band, which was in turn attached to the lower border of the bascinet by a series of staples called "vervelles". Holes in the leather band were passed over the vervelles, and a waxed cord was passed through the holes in the vervelles to secure it. The helmet also had a series of small holes around the bottom edge of the helmet and the face hole. These holes were used to sew a padded liner inside the helmet. The liner was made of linen or a linen blend cloth stuffed with wool or horsehair. The top of the liner was a series of lobes which were gathered by a cord to adjust how high the helmet rode on the wearer's head. While no known chin straps were used, the bascinet was often prevented from being lifted off the wearer's head by tying or strapping the camail to the surcoat or armour.
The bascinet, both with and without a visor (visors were often removable for better visibility and ventilation), was the most common helmet worn in Europe during the latter portions of the 14th and early 15th century, including during the Hundred Years' War. Contemporary illustrations show nearly every knight and man-at-arms wearing one of a few variants of the basic hounskull helmet. The basic design was intended to direct blows from weapons downward and away from the skull and face of the wearer. Over the course of the late 1300s to early 1400s, the bascinet evolved from a shorter form with a shorter point (or no point at all) to its more pointed form--some so severe as to have a vertical back. In Germany a more bulbous version also appeared in the beginning of the 15th century. During the first half of the 15th century, more plates were added to protect the throat better, producing a form called the "great bascinet". Both the portion covering the skull and the hinged visor over the face became less angular and more rounded, until by the mid- to late 1400s, the great bascinet had evolved into the armet.
Two styles of attaching the visor existed. The "klappvisor" was a single hinge at the front of the forehead that was commonly seen in Germany. The side-pivot mount used two pivots on the side of the helmet, which connected to the visor with hinges to compensate for the lack of parallelism in the pivots. The side-pivot system was commonly seen in Italian armours.
It is documented that some seasoned knights often wore their bascinets without visors for better visibility and breathing during hand-to-hand combat, and to avoid heat exhaustion.