means A deciduous tree of the genus Morus that bears clustered, blackberry-like edible fruit, famous as the sole food of silkworms.

from From Old English 'morberie,' a marriage of Latin 'morum' (mulberry, also the fruit of the bramble) and 'berie' (berry). The Latin itself traces back to Greek 'moron,' the mulberry fruit. Along the way the first 'r' softened into an 'l' — a common shift called dissimilation, where two similar sounds in a word drift apart so they're easier to say — turning 'mor-' into 'mul-.' The same Latin 'morum' is a cousin of the deep purplish-red we still call mulberry.