An evolved star which lies above the main sequence and below the giants on the Hertzsprung–Russell diagram, being less luminous than giant stars of the same temperature or spectral class.
Origin
1920s. From sub- + giant.
Definition of subgiant in US English:
subgiant
nounˈsʌbdʒʌɪənt
Astronomy
An evolved star which lies above the main sequence and below the giants on the Hertzsprung–Russell diagram, being less luminous than giant stars of the same temperature or spectral class.