Definition of "femtosecond"

Sheldon Cooper: My hair is growing at the rate of 4.6 yoctometers per femtosecond.

2012, Mark Cendrowski, The Big Bang Theory, Season 5, Episode 18, "The Werewolf Transformation"

The observation and manipulation of electron dynamics in matter call for attosecond light pulses, routinely available from high-order harmonic generation driven by few-femtosecond lasers.

2017, D. E. Rivas, A. Borot, D. E. Cardenas, G. Marcus, X. Gu, D. Herrmann, J. Xu, J. Tan, D. Kormin, G. Ma, W. Dallari, G. D. Tsakiris, I. B. Földes, S.-w. Chou, M. Weidman, B. Bergues, T. Wittmann, H. Schröder, P. Tzallas, D. Charalambidis, O. Razskazovskaya, V. Pervak, F. Krausz, L. Veisz, “Next Generation Driver for Attosecond and Laser-plasma Physics”, in Scientific Reports, volume 7