crun is actually a project that competes with runc. runc (run container) is implemented in go, and crun is a mostly drop-in reimplementation of it in C that is more faster and simpler, it's currently gaining traction in rhel/centos/fedora and suse linux as it was first to implement newer features such as cgroup v2.
Well.. it looks like .com domains : all 4-letters taken ;)
Other ideas: execc, cexec, cmk, mkc, exc, cex (my personal favorite :p).