A sentient computer was a computer system that had achieved sentience, showing signs like expressing emotions or desires, demonstrating meta-awareness, and displaying a "rudimentary sense of good and bad". Robots, holograms, and androids could fall under this category.

Cases that gained sentience

Exocomps were industrial and utility robots designed by the Tyran Doctor Farallon that later gained sentience, showcasing both self-preservation and self-sacrifice. (TNG: "The Quality of Life")

Vexilon was the computer that controlled the environment of Corazonia, an ancient Dyson ring. He was responsible for Corazonia's weather, geography, and day-night cycles. He displayed a kind and helpful countenance to the inhabitants of the ringworld, apologizing profusely whenever he committed an error. (LD: "In the Cradle of Vexilon")

A Soong-type android was created to achieve this over time due to both learning and experience (with an emotion upgrade to be provided at a later date). (TNG: "Datalore", "The Measure Of A Man", "The Offspring", "Inheritance"; Star Trek Nemesis) Eventually, Bruce Maddox and Soong's son Altan Soong, working together on Coppelius, were able to create sentient androids based on Noonien Soong's work. Altan was also able to create sophisticated golems that could house the sentience and personality of an established Soong-type's mind. (Star Trek: Picard)

Due to how the Emergency Medical Hologram (EMH) was created with contingency programs and adaptive programs to learn while serving as a supplement of a normal medical staff in cases of emergency meant that, given enough time and experience, they qualified as sentient computers. (VOY: "Ex Post Facto")