Plain English Meaning
A wing that is mostly self-supporting but still uses an external strut or two to help carry the load.
Full Definition
A wing design that is supported partly by its own internal structure and partly by external bracing, typically one or more struts running from the fuselage to the underside of the wing.
Context Anchor
Seen in discussions of wing construction and during preflight inspection of airplanes that have wing struts or other outside wing supports.
Derivation
From 'semi-' (Latin, meaning 'half' or 'partly') and 'cantilever' (an English engineering term for a beam supported only at one end). A cantilever wing has no external bracing; a semi-cantilever wing is partly cantilevered, with struts picking up the rest of the load.