Definition

Adjective: * Having a single cell (and thus not divided into cells): Describes a life form or organism whose entire body consists of just one cell. This single cell carries out all the functions necessary for life, such as feeding, moving, reproducing, and responding to the environment. It is not composed of multiple, specialized cells.

Usage

This adjective is used to classify and describe organisms in biology. It is typically placed before a noun or used after a linking verb like "is" or "are."

Examples

• Before a noun:
  • Bacteria are single-celled organisms.
  • The pond water was teeming with single-celled life.
  • Yeast is a single-celled fungus used in baking.
• After a linking verb:
  • An amoeba is single-celled.
  • Most protists are single-celled.

Advanced Usage

• The term is often used in contrast to "multicellular" (having many cells).
  • The evolution from single-celled to multicellular life was a major step.
• It can be hyphenated ("single-celled") or written as two words ("single celled"), but the hyphenated form is standard, especially when used before a noun.

Variants and Related Words

• Unicellular (adj.): This is a direct synonym, meaning "consisting of a single cell." It is more formal and technical.
  • Amoebas and paramecia are unicellular protists.
• Multicellular (adj.): The antonym, meaning "consisting of many cells."
  • Plants and animals are multicellular organisms.

Synonyms

• Unicellular
• One-celled

Antonyms

• Multicellular
• Many-celled

Adjective

1. having a single cell (and thus not divided into cells)