Meaning

noun (biology) the process of an individual organism growing organically; a purely biological unfolding of events involved in an organism changing gradually from a simple to a more complex level

noun a progression from simpler to more complex forms

noun a process of becoming larger or longer or more numerous or more important

originFrom grow + -th (abstract nominal suffix). Compare Old Frisian grēd ("meadow, pasture"; > North Frisian greyde (“growth, pasture”)), Middle High German gruote, gruot (“greens, fresh growth, shoot”), Old Norse gróðr ("growth, crop"; > Faroese grøði, Danish grøde (“fruits”), Swedish gröda (“crop, harvest”)). More at grow.

Etymology from Wiktionary, CC BY-SA 3.0