plural of Egyptian thorn

(botany) Vachellia nilotica subsp. nilotica, a perennial tree native to Africa.

Any desert-growing member of the genus Lycium

(idiomatic) A persistent annoyance.

plural of thorn in someone's side

Acacia luederitzii, a tree of Namibia.

(mathematics, physics) A theorem about certain vector spaces, relating to string theory.

plural of bastard umbrella thorn

(astronomy) A star that contains a core made from another star. It is formed when a neutron star collides with a star, typically a red giant or supergiant, and the neutron star is swallowed by the red giant star.

(figuratively) To enjoy a pleasant subject or thing, one must take trouble and hardship