ADJ.
under
VERB + COPYLEFT
believe, license, program
COPYLEFT + NOUN
licence
PREP.
in
noun
The philosophy of using copyrights to enforce freedom of information, especially software source code.
They believe in copyleft because they want their software to be used freely by anyone.
A software license that follows this philosophy.
I have placed my program under copyleft.
The GNU General Public License is a copyleft licence.
verb
To license under a copyleft license.
Linus Torvalds copylefted the Linux kernel.