cactus

American  

[kak-tuhs] / ˈkæk təs /

noun

plural

cacti, cactuses, cactus

1. any of numerous succulent plants of the family Cactaceae, of warm, arid regions of the New World, having fleshy, leafless, usually spiny stems, and typically having solitary, showy flowers.

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cactus British  

/ kækˈteɪʃəs, ˈkæktəs /

noun

1. any spiny succulent plant of the family Cactaceae of the arid regions of America. Cactuses have swollen tough stems, leaves reduced to spines or scales, and often large brightly coloured flowers

2. a double-flowered variety of dahlia

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Usage

Plural word for cactus The plural form of cactus can be either cacti, cactuses, or cactus. Cacti is most commonly used. Like many words derived from Latin, it is pluralized by replacing the -us ending with -i, as in fungus/fungi and nucleus/nuclei. However, the plural form cactuses, created by adding the typical -es to the end, is also correct. This alternative plural form is also acceptable for some other Latin-derived or related terms, as in focus/foci/focuses and radius/radii/radiuses.

Other Word Forms

• cactaceous
  adjective
• cactoid
  adjective
• cactuslike
  adjective

Etymology

Origin of cactus

1600–10; < Latin < Greek káktos cardoon

Explanation

A cactus is a succulent desert plant that's often covered in sharp spines. Some cacti grow brilliantly colored flowers, but none of them have leaves. You can grow an indoor cactus in a pot — it's a fairly easy plant to care for, since it prefers to be watered infrequently. Cacti are able to conserve water, which is why they do well in very dry environments, like the American Southwest. The Greek root of cactus is kaktos, the name of a specific spiky Sicilian plant.

Example Sentences

Even with such enormous variation, flower length showed almost no connection to how quickly new cactus species emerged.

From Science Daily • May 13, 2026

Aside from a cactus he waters once a month, he’s alone.

From The Wall Street Journal • Apr. 27, 2026

Dragon fruit is a climbing cactus, making it an unusual fruit to cultivate.

From BBC • Mar. 26, 2026

It takes in the affluent enclaves of Scottsdale and Paradise Valley and — where the urban sprawl finally yields to cactus, palo verde and other flora — Carefree and the Old West-themed Cave Creek.

From Los Angeles Times • Feb. 15, 2026

Roger Malecki says he put his entire cactus garden through his Magic Bullet blender, and extracted a gallon of water from it.

From "Dry" by Neal Shusterman and Jarrod Shusterman