window envelope window-efficiency ratio • window fixture · · · Info · Definitions · Characters · · window envelope · · Text Common · · Latin · · Scripts 15 · · Length 5 · · Syllables Definitions · · · (noun) an envelope with a transparent panel that reveals the address on the enclosure. Synonyms: window envelope. · · Noun Definition 1 Characters · · space U+0020 d latin small letter d U+0064 e latin small letter e U+0065 i latin small letter i U+0069 l latin small letter l U+006C n latin small letter n U+006E o latin small letter o U+006F p latin small letter p U+0070 v latin small letter v U+0076 w latin small letter w U+0077