Use of the name Dirac and the words honeycomb and ribbon has grown almost exponentially since the experimental realization of graphene (stressed on the second syllable) in 2004. Because of its shape, the hexagonal pattern in which carbon atoms are arranged in graphene is called a honeycomb lattice. On such a lattice, electrons near the so-called Dirac points have a linear relation between energy and momentum, as described by the Dirac equation. A graphene ribbon is a typically narrow (compared to its extent in the other direction) sheet of graphene, reminiscent of the shape of a ribbon.
Despite their popularity, the words Dirac, honeycomb, and ribbon are often mispronounced by scientists.
For Dirac, the Longman Pronunciation Dictionary gives the following possible pronunciations:
The first two variants only differ in terms of stress. The rather common incorrect pronunciation is [daɪˈræk], possibly related to the most common pronunciation of direct, [daɪˈrekt]. However, the word direct can also be pronounced in three different ways, namely (listen here) [daɪˈrekt], [dɪˈrekt], and [dəˈrekt].
The word honeycomb is a rather rare case of a compound English word that is pronounced just as its components, namely honey and comb. The mistake many non-native speakers make is to ignore the fact that the letter b in comb is silent, see here. The correct pronunciation of honeycomb therefore is
You can listen to it here.
Finally, the correct pronunciation of ribbon is given by