Dictionary midstreamDuring a process

adverb

midstream

mid-STREEM/mˈɪdstrˌim/

In the middle of an activity or process.

The carpenter's work is interrupted midstream, with the chair still partly assembled.

A carpenter interrupted midway through assembling a chair, half-finished chair in hands and unassembled matching parts on bench, activity visibly in progress rather than complete, no writing.

Etymology

midstreamOld EnglishThe middle of a stream.

Being in the middle of a stream became a metaphor for being in the middle of a process.

More examples

Changing suppliers midstream would be difficult.
They rewrite the rules midstream.

Forms

midstream

Similar words

midway: At an intermediate point, often literally in time or distance.
during: Means within a period without implying its middle.