Open-source

adj.hopeful, capableprofessional

What it means

Freely available for people to inspect, use, and improve.

Reach for it when describing software whose source code is available under a license permitting use and modification

Students improved the open-source tool for readers with low vision.

everyday
publicly developed
development happens in visible community channels
not when Public development does not establish license rights.
warm
community-built
distributed contribution is being celebrated
not when Community-built software can still be proprietary.
professional
free software
user freedoms are the philosophical and legal focus
not when Free refers to liberty, not necessarily price.
professional
source-available
code can be inspected under stated terms
not when Source availability may forbid modification or commercial use.
formal
openly licensed
permissions are granted by a named license
not when A license can be open for content but not software.
literary
libre
freedom to use and modify needs a compact contrast with gratis
not when Libre is specialist terminology in English.

open-source software
The school adapted open-source software for low-vision readers.
open-source license
An approved open-source license made reuse terms explicit.
open-source project
The open-source project publishes its roadmap and review process.

Open-source requires an actual qualifying license; visible code, zero price, public development, and open standards are separate properties.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.