CLA (Contributor License Agreement)
An agreement a contributor signs before a project accepts their code, giving the project's owner broader rights than the license itself would.
A CLA can be a broad license to the project, like the Apache Software Foundation's, or an outright transfer of copyright, as GNU projects long required so the FSF alone could enforce the license in court. The stated purpose is legal hygiene: the project knows the person submitting the code actually had the right to.
The less advertised effect is that the owner can relicense everything. That is what makes dual licensing possible, and what HashiCorp relied on in 2023 when Terraform moved to a source-available license. Plenty of developers therefore read a CLA as a warning sign and prefer the lighter DCO, which hands over nothing beyond the license.