The plural of the word shield is shields.
The plural of may is the same word (still may)
Greatest is an adjective. It has no plural because it is not a noun.
The plural for for the noun glass is glasses.
rhombuses
The plural of cone is cones.
If you mean the cone shaped hat with tassels, then the plural word is fezzes.
The Scottish word for pine cone is "tappie".
The word crises is a plural word; it is the plural form of the word crisis.
There is 1 syllable in cone.
snow cone
The cone is the apex of the volcano.
There is no plural word for if.
Cone flower = pua ekineikea
The plural form for the demonstrative pronoun this is these.
A non-plural word, a word (noun or pronoun) that is not plural is singular, a word for just one.
The plural word of delay is delays.