1) Genre of poetry 
A grook (`gruk` in Danish) is a form of short aphoristic poem. It was initially presented by the Danish poet and scientist Piet Hein, who wrote over 7000 of them, mostly in Danish or English. They have been published in 20 volumes. Some say that the name is short for `GRin & sUK` (`laugh & sigh` in Danish), but Piet Hein said he felt that th...