Cedrus libani, commonly known as cedar of Lebanon, Lebanon cedar, or Lebanese cedar (Arabic: أرز لبناني, romanized: ʾarz lubnāniyy), is a species of large evergreen conifer in the genus Cedrus, which belongs to the pine family and is native to the mountains of the Eastern Mediterranean basin. Known for its longevity, height, and durable wood, it has held profound significance for millennia. The tree features in ancient Mesopotamian and Israelite literature, notably in the Hebrew Bible, according to which the tree was used in the construction of the Jerusalem Temple by Solomon, who received the trees from Hiram of Tyre. Today, it is the national emblem of Lebanon and is widely used as an ornamental tree in parks and gardens.

Cedrus libani can reach 40 m (130 ft) in height, with a massive monopodial columnar trunk up to 2.5 m (8 ft 2 in) in diameter. The trunks of old, open-grown trees often fork into several large, erect branches. The rough and scaly bark is dark grey to blackish brown, and is run through by deep, horizontal fissures that peel in small chips. The first-order branches are ascending in young trees; they grow to a massive size and take on a horizontal, wide-spreading disposition. Second-order branches are dense and grow in a horizontal plane. The crown is conical when young, becoming broadly tabular with age with fairly level branches; trees growing in dense forests maintain more conical shape.

The shoots are dimorphic, with both long and short shoots. New shoots are pale brown, older shoots turn grey, grooved and scaly. C. libani has slightly resinous ovoid vegetative buds measuring 2 to 3 mm (0.079 to 0.118 in) long and 1.5 to 2 mm (0.059 to 0.079 in) wide enclosed by pale brown deciduous scales. The leaves are needle-like, arranged in spirals and concentrated at the proximal end of the long shoots, and in clusters of 15–35 on the short shoots; they are 5 to 35 mm (0.20 to 1.38 in) long and 1 to 1.5 mm (0.039 to 0.059 in) wide, rhombic in cross-section, and vary from light green to glaucous green with stomatal bands on all four sides.

Cedrus libani produces cones beginning at around the age of 20–40. Its cones are borne in autumn, the male cones appear in early September and the female ones in late September. Male cones occur at the ends of the short shoots; they are solitary and erect about 4 to 5 cm (1.6 to 2.0 in) long and mature from pale green to pale yellow-brown. The female seed cones also grow at the terminal ends of short shoots. The young seed cones are resinous, sessile, and pale green; they require 12 months after pollination to mature. The mature, woody cones are 8 to 12 cm (3.1 to 4.7 in) long and 3 to 6 cm (1.2 to 2.4 in) wide; they are scaly, resinous, ovoid or barrel-shaped, and green ripening to grey-brown the autumn after pollination. Mature cones open from top to bottom, they disintegrate and lose their seed scales, releasing the seeds until only the cone rachis remains attached to the branches.

The seed scales are thin, broad, and coriaceous, measuring 3.5 to 4 cm (1.4 to 1.6 in) long and 3 to 3.5 cm (1.2 to 1.4 in) wide. The seeds are ovoid, 10 to 14 mm (0.39 to 0.55 in) long and 4 to 6 mm (0.16 to 0.24 in) wide, attached to a light brown wedge-shaped wing that is 20 to 30 mm (0.79 to 1.18 in) long and 15 to 18 mm (0.59 to 0.71 in) wide. C. libani grows rapidly until the age of 45 to 50 years; growth becomes extremely slow after the age of 70.

Cedrus is the Latin name for true cedars. The specific epithet refers to the Lebanon mountain range where the species was first described by French botanist Achille Richard; the tree is commonly known as the Lebanon cedar or cedar of Lebanon. Two to three distinct types are accepted as varieties: C. libani var. libani, C. libani var. brevifolia, and C. libani var. stenocoma; the last not being considered distinct by all authorities.

C. libani var. libani: Lebanon cedar, cedar of Lebanon – grows in Lebanon, western Syria, and south-central Turkey. C. libani var. stenocoma (the Taurus cedar), considered a subspecies in earlier literature, is now considered as a variety or ecotype of C. libani var. libani. It usually has a spreading crown that does not flatten. This distinct morphology is a habit that is assumed to cope with the competitive environment, since the tree occurs in dense stands mixed with the tall-growing Abies cilicica, or in pure stands of young cedar trees. Isozyme analysis however placed var. stenocoma closer to var. brevifolia than to var. libani, even placing var. brevifolia embedded within var. stenocoma samples.

C. libani var. brevifolia: The Cyprus cedar occurs on the island's Troodos Mountains. This taxon was considered a separate species from C. libani because of morphological and ecophysiological trait differences. It is characterised by slow growth, shorter needles, and higher tolerance to drought and aphids. Genetic relationship studies, however, did not separate C. brevifolia as a separate species, the markers being indistinguishable from those of C. libani.