Sentience was the ability to think intelligently.
A sentient was a being with the ability to think intelligently, commonly determined by the being's ability to speak, manipulate tools, and reason. Species that lacked this ability were classified as non-sentient, or sometimes as sub-sentient. Species that appeared to have emerging sentience were classified as semi-sentient. These included species that had very primitive capabilities to manipulate tools, use language, and/or solve problems. Examples included the Arkanian dragon, the Bafforr tree, and the Darkstaff.
An Annual Mid-Rim Domesticated Sub-Sentient Show was held for non-sentient creatures. The Galactic Empire would often recategorize sentient species such as the Wookiees as non-sentient, allowing it to enslave them without formally violating the laws protecting sentient beings from such abuse.
The term sentient is technically incorrect for this usage, instead referring to any being with the capacity to feel sensations, such as pain; thus, most animals are sentient. More correct terms include sapient and sophont.
Sentient comes from the Latin word sentire, meaning "to feel."