Meaning & use
biaxial symmetry
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Meanings
noununcountabletechnical
A property of an object or crystal in which its shape or structure repeats when rotated 180 degrees around each of two different axes.
Grammar: Used as a mass noun: say 'the crystal shows biaxial symmetry', not 'a biaxial symmetry'.
Patterns
- something has biaxial symmetry
- the biaxial symmetry of something
- exhibit biaxial symmetry
The mineral sample was studied for its biaxial symmetry under a polarizing microscope.
Students learned that biaxial symmetry requires two distinct axes of rotation, not just one.
The pattern on the tile has biaxial symmetry, so it looks the same after a half turn either way.
noununcountablebiologytechnical
In biology, a body plan that can be divided into mirror-image halves along two different planes.
Grammar: Common in zoology texts; often followed by 'in' plus a group of animals.
Patterns
- biaxial symmetry in something
- show biaxial symmetry
- a form of biaxial symmetry
Some simple marine animals are described as having biaxial symmetry rather than radial symmetry.
The textbook contrasted biaxial symmetry with the single plane of symmetry found in many flatworms.
Researchers debated whether the fossil showed true biaxial symmetry or an irregular shape.
Common combinations
- show biaxial symmetry
- The crystal was found to show biaxial symmetry when viewed from two directions.
- the biaxial symmetry of a crystal
- The biaxial symmetry of a crystal affects how light travels through it.
- lack biaxial symmetry
- Most everyday objects, such as a spoon, lack biaxial symmetry.
- a plane of biaxial symmetry
- The diagram marks each plane of biaxial symmetry with a dashed line.
Synonyms and how they differ
- twofold symmetry
- A looser everyday phrase for a shape that repeats twice around an axis; it does not specify two separate axes as precisely.
- orthorhombic symmetry
- A crystallography term for a related crystal system; it describes a whole class of structures, not just the two-axis property.
Opposites
Word family
- biaxial adjective
- Having or relating to two axes.
- axial adjective
- Relating to an axis or a line around which something turns.
- symmetrical adjective
- Having parts that match on opposite sides of a line or center.
- symmetry noun
- The quality of having matching parts on opposite sides.
Commonly confused: biaxial symmetry or bilateral symmetry? biaxial symmetry or radial symmetry?
biaxial symmetry vs bilateral symmetry
Bilateral symmetry means one plane divides the body into two matching halves, as in humans; biaxial symmetry involves two such axes of rotation.
biaxial symmetry vs radial symmetry
Radial symmetry repeats around a single central point, like a starfish, whereas biaxial symmetry repeats around two different axes.
Practice
A crystal that looks the same after a half turn around each of two different axes is said to have ___.
Choose one answer.
'Biaxial symmetry' names exactly this two-axis property. 'Radial symmetry' repeats around a single center, and 'asymmetry' means no symmetry at all.
Make it your own
Write a sentence using “biaxial symmetry”, then check it and compare it with the examples above.