Migrant
The only 8 letter word with those letters is "poaching"
Tagalogs
Postages contain 8 letters. It uses the letters TPGSSAOE.
There's only 7 leters there. The biggest word is taggy.
Original
No eight letter words match that description. However, a seven letter word, basking, and a six letter word, asking, contain a portion of those letters.
The word, 'astonishing' uses all of the given letters.
Eagerest
I can not identify any 8 letter words. However, the letters do spell the 7 letter words agendas and savaged.
Singularity
None in either the Scrabble dictionary or Webster's Second International.
The letters can be used to spell the 8 letter word unseemly and the 7 letter words legumes and lungees . They also spell the 6 letter words seemly, smugly and snugly.