In this present manuscript, ultrasmall copper nanoparticles (UCuNPs) was synthesized by Terminalia bellirica fruit extract as a reducing agent. The method of synthesis is ecofriendly, single step, aqueous and ambient method. As synthesized nanoparticles were in diameter of 2-7 nm. The surface plasmone resonance is observed with UV-visible spectrophotometry, UCuNPs are nonplasmonic. Fourier transform infrared spectroscopy indicates that oxygen-containing functional groups in the T. bellirica fruit extract are involved in the nanoparticle synthesis reaction. High-resolution transmission electron microscopy (HRTEM) was used to confirm that the UCuNPs are spherical shape. XRD analysis confirms that the nanoparticles are single crystalline. X-ray energy dispersive spectroscopy conducted during HRTEM analysis confirms the presence of pure copper in the sample. The particle size analysis is also confirms that the particles were polydispersed. The stability of UCuNPs characterized by zeta potential. We are also done antimicrobial activity (anti bacterial and anti fungal) of UCuNPs shown good activity.