public static string ToPluralNoIrregular(string noun)
{
// check if word ends in sibilant sound
if (sibilantEndings.Any(x => noun.EndsWith(x)))
return noun + "es";
if (noun.EndsWith("y"))
return noun.Substring(0, noun.Length - 1) + "ies";
if (noun.EndsWith("f"))
return noun.Substring(0, noun.Length - 1) + "ves";
if (noun.EndsWith("fe"))
return noun.Substring(0, noun.Length - 2) + "ves";
return noun + "s";
}