Landmass rhymes with:
airgas, amerigas, bluegrass, boardingpass, bumpass, bypass, eelgrass, energas, eyeglass, fiberglas, fiberglass, hourglass, jackass, outclass, overpass, piepgras, plexiglas, plexiglass, sassafras, serfass, shortgrass, snodgrass, spyglass, sunglass, tallgrass, trespass, underclass, underpass, upperclass, worldpass, yankass
Landmass sounds like:
lamenting, laminating, landing, landings, landmasses, landmines, landon's, lanting, lanting's, lending, lendings, limitations, limiting, linden's, london's