- A value in a header which indicates whether a given packet has exceeded the time or number of hops it is permitted for travel within a network. Bad routing, for instance, may lead to a packet to otherwise go through endless loops. When the value reaches zero, the packet is discarded and an error message is sent to the originating host. Its abbreviation is TTL.
- noun the most common family of logic gates and high-speed transistor circuit designs in which the bipolar transistors are directly connected, usually collector to base.