Directional intermolecular interactions play a key role in many physical and biological processes. In particular, hydrogen bonds play a central role in protein-ligand binding [1] and in maintaining the stable secondary structure of proteins. But what is a hydrogen bond? Can we discover the presence of hydrogen bond, and define the characteristic features of hydrogen-bonding interactions, directly from data? To elucidate hydrogen bonding, we analyze liquid-phase molecular dynamics trajectories to discern highly probable directed intermolecular interactions. Our approach clusters high-dimensional data using kernel density estimation and gaussian processes, then dimensionality reduction to find a geometric parameterization for hydrogen bonding. The proposed approach is validated by revealing the FH...F bond in hydrogen fluoride and the OH...O bonds in water and methanol. Equilibrium geometries of dimers in the studied systems are found to be consistent with results available in the literature. The average lifetime of the OH...O type hydrogen bond and its temperature dependence are determined, and found to be consistent with results from inelastic neutron scattering experiments. [1] R. Ferreira de Freitas and M. Schapira, “A systematic analysis of atomic protein–ligand interactions in the PDB,” Med. Chem. Commun., vol. 8, no. 10, pp. 1970–1981, 2017, doi: 10.1039/c7md00381a.