Answer:
These are nouns which are plural and is also considered as singular...
They are used in a plural and singular sentences...
words which are examples of nouns which are singular and plural:
molasses, physics, measles, mumps, homologous, Bass, Bus, Dress, Hippopotamus, Iris, Lass, Truss, Walrus, press, glass, octopus, moss, boss, floss, ass, pass, loss, news, gloss, bliss, Mass, buss,kiss, miss, chess, cross, fuss,plus, guess, caress, morass, duress, success, platypus, moss, lens, abyss, access, excess, stress, tress, hiss, less, mess, chess, cress, address, redress, regress, compress, cypress, impress, progress, transgress, piss, puss, pus, yes, gas, grass, floss, toss, gross, dross, minus, trousers, pants, mantis, diabetes, scissors, shears, tweezers, tongs, muss, vespers