container

Freight made this box a fixed size. The ISO container is 8 feet wide and was originally 8 feet tall, a height since raised to 9 feet 6 inches, and it comes in a range of lengths. In 1963, Modern Railways was still asking whether it would do more than replace the covered wagon. Shipping container and cargo container name the same box and keep it apart from the household kind.

The general sense that the rest specialize. Middle English conteyner is simply contain plus the agent suffix -er, so anyone or anything that contains qualifies. Here the stress falls on enclosing rather than on storing or shipping, and that is what separates it from the everyday storage meaning. Every technical use of the word, from the steel freight box to the software bundle, keeps this one idea of holding something within.

Cloud engineers place this container between two older ideas. Elton Stoneman's Learn Docker in a Month of Lunches (2020) describes containers as isolated like virtual machines yet lightweight and efficient like platform services. They are often short-lived, and serverless code is described as running on ephemeral containers. Software container is the unambiguous name, and the word stretches from the bundle to the running environment itself.

Programmers use the word as a family name for data structures such as lists, vectors, deques, sets and maps. Choosing among them is a matter of trade-offs. Ivor Horton's Using the C++ Standard Template Libraries (2015) weighs a list container against a vector or a deque. The word usually travels as a modifier after the specific type, as in list container, so the kind is named first and the family second.

Interface builders think in trees. A container holds child components and may itself be the child of another container. In Adobe Flex, a TabNavigator container gets a TabBar container across its top, with one tab for each child container. Panels, frames and windows are the usual examples. The word stresses holding and arranging other components rather than displaying anything of its own.

In media files the container is the wrapper, not the content. MP4 can hold audio, video or both, which is why an MP4 carrying only sound is given the M4A name and extension as a hint. The container fixes how the streams are stored together, not how each one is encoded. The fuller term container format makes that distinction explicit.

Java's server vocabulary has its own container. It is the part of an application server that implements the servlet and JSP specifications, and it is also called a servlet container. Servlets do not start themselves: the container decides when one is created, which request it receives and when it is retired. Despite the shared name, it is a different thing from the packaged software bundle.

Solvers learn to spot this device by its indicator words, and those words are slippery. 'In' has several uses, 'round' or 'around' may signal a container or a reversal, and 'without' may signal a container or a deletion. The word works mostly as a modifier, as in container clue, container indicator or container device. Such clues often combine with other devices in harder puzzles.