bilateral symmetry

noun

, Biology.

1. a basic body plan in which the left and right sides of the organism can be divided into approximate mirror images of each other along the midline.

bilateral symmetry

noun

1. the property of an organism or part of an organism such that, if cut in only one plane, the two cut halves are mirror images of each other See also radial symmetry

bilateral symmetry

/ bī-lăt′ər-əl /

1. Symmetrical arrangement of an organism or part of an organism along a central axis, so that the organism or part can be divided into two equal halves. Bilateral symmetry is a characteristic of animals that are capable of moving freely through their environments.
2. Compare radial symmetry

Word History and Origins

Origin of bilateral symmetry¹

First recorded in 1850–55

Example Sentences

According to the new study, bilateral symmetry -- where there is only one line that divides the flower into two equal halves -- has evolved and been lost multiple times independently in sunflowers over evolutionary history.

From Science Daily

"With our increased sample size, we were able to resolve more of the smaller branches and twigs at the subtribe and genus level. This higher-resolution tree allowed us to reconstruct where and when traits like flower symmetry evolved, demonstrating that bilateral symmetry must have evolved many times independently."

From Science Daily

Sea anemones are from a different branch of the animal tree; they have only two layers of cells and radial rather than bilateral symmetry.

From Science Magazine

The scientists behind it say the development of bilateral symmetry was a critical step in the evolution of animal life.

From BBC

It didn’t help that they lacked bilateral symmetry, that their long stalks with blobby appendages appeared to human eyes to be distributed totally randomly.

From Nature