From Sherlock + -ish.
Sherlockish (comparative more Sherlockish, superlative most Sherlockish)
- Resembling or characteristic of the fictional detective Sherlock Holmes.
1938 March 11, Sophie Kerr, “There's Only One”, in The Massena Observer, page 4:Curt chuckled. "You sound so important and Sherlockish! […]
2001 June 12, thurmans, “Re: Bye Bye Black Sheep - Chapter 9”, in alt.fan.travis-mcgee[1] (Usenet):It's starting to come together nicely, and Meyer's character is starting to ring truer, although perhaps a bit to[sic] Sherlockish.
2007 July 20, Vladimir Makarenko, “Re: Kreml Sends 80 Year-old Bombers To Scare UK”, in soc.culture.baltics[2] (Usenet):Or another attempt on Berezovsky's life stopped by sherlockish Scotland Yard.