[en] Highlights: • Dielectric spectroscopic study of five alcohols at 0.5 to 10 THz frequency range. • Model with one Debye and three harmonic oscillators fits the experimental spectra. • MD simulations and ab initio calculations reveal the vibrational modes observed. • H-bond breaking and making, and the motions alkyl chains and H-bonded OH groups. We have studied the complex dielectric properties of a series of alcohols in 0.5–10 THz frequency range using THz time-domain spectroscopy. The dielectric response observed has contribution from a Debye relaxation process and three damped harmonic oscillators. Combination of experimental observations, all-atom molecular dynamics simulations and ab initio quantum calculations reveals that the complex dielectric spectra of alcohols result from a complex dynamics involving vibrational motions of several atoms across multiple interacting alcohol molecules. The major contribution comes from the fast hydrogen-bond rupture and reformation dynamics, the motion of alkyl chains, and the motions of the H-bonded OH groups.