Yes, but not for the concept, only for "customs" or "gatherings" which are conventions.
There is no plural form. Do and Do not are verbs
The plural form of him, her, or it is them. (objective pronouns)
The plural form of "is" is "are."
The plural form of "was" is "were."
The plural form of mouth is mouths. The plural form of month is months. The Mounth is a range of hills in Scotland and does not have a plural form.
The plural of convention is conventions.
The plural of "amethyst" is "amethysts." This follows the standard English convention of adding "s" to form the plural for most nouns. Amethyst refers to a purple variety of quartz used as a gemstone, and the plural form is used when referring to more than one of these stones.
There is no plural form. Do and Do not are verbs
The plural form of him, her, or it is them. (objective pronouns)
Bridges is the plural form of bridge.
The plural form of "is" is "are."
The plural form of "was" is "were."
The plural form of mouth is mouths. The plural form of month is months. The Mounth is a range of hills in Scotland and does not have a plural form.
"Groceries" is the plural form of "grocery."
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
The plural form of the demonstrative pronoun 'that' is those.
Trenches is the plural form.