The noun clothing is an uncountable noun (mass noun), or a collective noun for a type of something. To indicate singular it is phrased as 'a piece of clothing' or 'an article of clothing'.
In this case, "girls" is plural possessive because it indicates that the clothing belongs to more than one girl. If it were singular possessive, the statement would read: "the little girl's clothing is on the first floor."
The noun 'clothing' is an uncountable noun, a type of aggregate noun, a word representing an indefinite number of elements or parts. The noun 'clothing' takes a verb for the singular.Example: This clothing is going to the dry cleaner.
There isn't really a singular form for the word 'clothes'... but you can say "article of clothing" or "garment" or just say what kind of clothes you're talking about (shirt, pants, shoes, etc)
The noun "clothing" is generally treated as a singular noun and takes singular verbs. For example, "The clothing is on sale" or "This clothing brand is popular." However, in certain contexts where "clothing" refers to individual items, plural verbs can be used. For example, "These clothing items are unique."
The singular form of the demonstrative pronoun 'these' is this.
The noun 'clothes' always appears in the plural and does not have a singular form. To express the idea of 'clothes' as a singular thing, you would normally say 'a piece of clothing' (everyday language) or 'an article of clothing' (formal language).
The singular form of "that" is "it."
The singular form of "cuffs" is cuff.
The singular form of "stratum" is "stratum." The word does not change in its singular form.
The singular form of feet is foot.
The singular form of "oases" is "oasis."
The singular form of "wash" is "washing."