Mammoth Uncensored Word List:
59 - 12 letter words starting with go

goalkeepings goalkickings goaltendings gobbledegook gobbledygook gobletshaped goddamnedest goddaughters goddesshoods godfathering godmothering goldbrickers goldbricking goldennesses goldilockses goldsmithery goldsmithing goliarderies goliathising goliathizing gollywhomper gonadotropic gonadotropin gonarthritis gonfaloniers goniatitoids gonimoblasts goniometries goodbreeding goodhumoured goodlinesses goodtempered goofproofing googlewhacks googolplexes gooseberries goosefleshes goosegrasses goosestepped gorgeousness gorillagrams gormandisers gormandising gormandizers gormandizing gospellising gospellizing gossipmonger gourdinesses gourmandised gourmandises gourmandisms gourmandized gourmandizes gouvernantes governessing governmental governorates governorship