homologue

A scientist compares the chemical structure of a homologue on a chart.

Definition

1. Noun:
   • Corresponding part or structure: In biology, a "homologue" refers to an organ, structure, or part that is similar in origin and position in different species, indicating a common evolutionary ancestry. For example, the forelimbs of humans and bats are homologues.
   • Corresponding chemical compound: In chemistry, a "homologue" is a member of a series of organic compounds that differ from each other by a fixed unit, typically a methylene group (CH₂). For instance, methane (CH₄) and ethane (C₂H₆) are homologues in the alkane series.

Usage Examples

• (Biological structures with evolutionary similarity.)
• (Chemical compounds in the same homologous series.)

Advanced Usage

• "to be a homologue of": to share a fundamental similarity in origin or structure.
  • The human thumb is a homologue of the panda's "thumb," which is actually a modified wrist bone. (Both structures evolved from the same ancestral bone.)

Variants and Related Words

• Homologous (adj): having a similar position, structure, or evolutionary origin.

  • The forelimbs of whales and horses are homologous structures. (They share a common ancestry despite different functions.)

• Homology (n): the state of being homologous; similarity due to common descent.

  • The homology between the bones of the human hand and the bat wing is clear. (The structural similarity indicates shared ancestry.)

Synonyms

• Counterpart: a person or thing that corresponds to another in function or position.
• Analog: a structure or part that is similar in function but different in origin (contrast with homologue, which emphasizes shared origin).

Related Idioms