Sukuk are financial instruments, such as certificates, that have economic similarities to bonds (www.practicallaw.com/0-107-6503) but are structured so as to comply with Sharia (www.practicallaw.com/resource.do?item=:23982768). Corporate sukuk are sukuk issued by a body corporate, rather than a sovereign issuer.
The singular of sukuk is sakk, but sukuk is sometimes used colloquially as the singular and sukuks as the plural.