Wiktionary
n. (context colloquial English) A placeholder for the name of a man whose name the speaker can not bring to mind.
Usage examples of "whatsisname".
I guess Springbuck and Van Duyn and the others got to whatsisname, Reacher?
Then whatsisname and I, Springbuck, will do one, repeat, one fast dismounted scout.
I suggest you go to Porto Alegre, tell Colonel Whatsisname that I'm on the way, and get your people ready.
You lose any sleep when whatsisname did it, three-four years ago, the French kid, the writer?
Also a couple of people around Larry Whatsisname the magazine publisher.
Even a cursory glance around the kitchen tells me that there's a strong theatrical bias to the guest-list - most of the chorus of The Bacchae are here, all talking at once, and Neil whatsisname, star of last term's acclaimed modern-dress production of Richard III is leaning on the fridge, talking amiably with the Duke of Buckingham, and Antigone, one of the hosts, is emptying cheesy wotsits into a big bowl.