Synonyms for Plank (same or very similar meaning)
WordNet sense 1 (a stout length of sawn timber; made in a wide variety of sizes and used for many purposes):
boardWordNet sense 2 (set (something or oneself) down with or as if with a noise):
plop, plump, plunk, flump, plonk, plump down, plunk downWordNet sense 3 (cover with planks):
plank overFrom the ODE community, based on WordNetadd/edit