Uptime is a measure of the time a machine has been up without any downtime.
It is often used as a measure of computer operating system reliability or stability, in that this time represents the time a computer can be left unattended without crashing, or needing to be rebooted for administrative or maintenance purposes.
Conversely, long uptime may indicate negligence, because some critical updates can require reboots on some platforms.
Uptime Synonyms or related words for this sense of uptime: Although not commonly used, this expression is spoken in some places in the South of England with the meaning of cool. Coolness is an admired aesthetic of attitude, behavior, comportment, appearance and style, influenced by and a product of the Zeitgeist. Because of the varied and changing connotations of cool, as well its subjective nature, the word has no single meaning. It has associations of composure and self-control (cf. the OED definition) and often is used as an expression of admiration or approval. Although commonly regarded as slang, it is widely used among disparate social groups, and has endured in usage for generations.