rare

Very uncommon; scarce.

Black pearls are very rare and therefore very valuable.

Plant breeding is always a numbers game.[…]The wild species we use are rich in genetic variation, and individual plants are highly heterozygous and do not breed true. In addition, we are looking for rare alleles, so the more plants we try, the better.

Small in number (but not unusual); infrequent; sparse.

The anterior and posterior skin of the upper chest and shoulders demonstrated irregularly jagged borders with areas of soot and charring focally. The soft and bony tissues underlying the borders were markedly damaged by presumed explosive injuries. There were rare abrasions and contusions of the chest and upper extremities. The lower extremities demonstrated rare abrasions and contusions as well as severe lacerations of the anteromedial knees with underlying fractures of the distal aspects of the femora (Image 4).

Moreover, the SF [Superficial fascia] splits to surround vessels and nerves, ensuring their patency, and forms the so-called retinacula cutis, which has the function of connecting the SF to the skin (retinacula cutis superficialis, or skin ligaments) and to the deep fascia (retinacula cutis profundis), to provide a dynamic and flexible anchor of the skin to underlying tissues [16,20]. The deep septa are rare, thin, and oblique and have an apparent lesser organization, allowing great autonomy between superficial and deep fascia.

Thin; of low density.

Good; enjoyable.

Sees her reflection in a butcher shop. She finds it all quite rare That her meat's all vanity fair.

A scarce or uncommon item.

Most of the time, you do this by trading low-valued rares for more valuable ones or trading uncommons for rares. Other times it's trading cards that are in print for ones that are out of print, or low-value rares for good uncommons.

Particularly of meat, especially beefsteak: cooked very lightly, so the meat is still red.

Then Curds and Cream, the Flow'r of Country Fare, / And new-laid Eggs, which Baucis’ buſie Care / Turn’d by a gentle Fire, and roaſted rare.