In a Webster's Dictionary entry:imper.
Dictionary: Of the English Language/Indexed/Imperial Buckram/Unabridged ... 
American dictionary available, containing over 472,000 entries, 14,000 new 
words in a... [DOC] [TLE] Webster's Dictionary | Open Access articles | Open Access journals ... [PAR] An 1888 advertisement for Webster's Unabridged Dictionary .... use of pictorial 
illustrations integrated with the text, The Imperial Dictionary, English, ...