verb

(of a living thing) undergo natural development by increasing in size and changing physically.

he would watch Nick grow to manhood

get bigger,get taller,get larger,increase in size,increase in weight,fill out,fatten,heighten,lengthen,enlarge,extend,expand,stretch,spread,widen,swell,increase,multiply,snowball,mushroom,balloon,augment,build up,mount up,pile up