1. Precociousness.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• precotious,
• preconcious,
• precosious,
• precatious,
• precurious,
• precusious,
• precvious,
• precoscious,
• precousious,
• precsious,
• precocioun,
• preccious,
• prescious,
• preciious,
• percocious,
• preacious,
• precoious,
• precoius,
• preceious,
• precuious

• preciosity,
• projection,
• preciously,
• precess,
• prosecution,
• precook,
• precooked,
• preciousness,
• projectionist,
• projector,
• precocity,
• precision,
• precious,
• precast,
• precociously,
• precocial,
• precisely,
• precise.

The adjective form of the word "precocious" is "precocious". The word "precocious" is already an adjective that describes a child who develops certain abilities or talents at an earlier age than usual.

The plural form of the word "precocious" is "precociouses" or "precocious".

The singular form of the word "precocious" is "precocity"