From the Harvard dictionary of Music: poco means ' little', and ritardando means
"gradually lackening in speed' ( or, slowing down ).
SO,it means a small--not very much- slowing up of the tempo.
The term is Ritardando.
Ritardando is a musical term meaning to gradually slow down in tempo.
rit. or ritard.
In music, senza ritardando means without slowing, in other words keep the tempo.
adagio Ritardando ... the term 'adagio' is a tempo, not the act of slowing down.