certainty, inevitability, necessity

the front, the part in front / façade

nature, specifically its personification Mother Nature

perfect, flawless

perfection

(aeronautics) leading edge

improvement, an action taken to improve / improvement, a spontaneous change for the better

(transitive) to improve, to make better / (intransitive) for something to improve on its own

(anatomy) prostate

(idiomatic) An unheard of, unprecedented issue.