Neuter nouns behave like masculine nouns in the singular and like feminine nouns in the plural form. "Măr " (apple as a fruit) is a neuter noun, therefore "un măr", "două mere." However, "măr" can also mean "apple tree." In this case it is a masculine noun: "măr" = apple tree (sg); "meri" = apple trees (pl)
True. Additionally, all compound numbers ending in 1 or two are gendered, except for 11. 11= unsprezece
Unsprezece fete (eleven girls) // unsprezece băieţi (eleven boys)
12 = doisprezece (masculine) // douăsprezece (feminine).
We say: doisprezece cartofi = twelve potatoes (cartof is a masculine noun)
douăsprezece ouă = twelve eggs (ou is a neutral noun, therefore it behaves like feminine nouns in the plural form and like masculine nouns in the singular form).
Here's the rule for one-two:
Un - doi --> masculine nouns ("un" for singular; "doi" for plural). Ex: un băiat, doi băieţi
O - două --> feminine nouns ("o" for singular; "două" for plural). Ex: o fată; două fete
Un - două --> neuter nouns ("un" for singular; "două" for plural). Ex: un scaun (a chair), două scaune .
Remember that neuter nouns behave like masculine nouns in the singular and like feminine nouns in the plural.
The Romanian indefinite articles are: un --> singular masculine and neuter nouns
o --> singular feminine nouns
nişte --> all plural nouns
From Vulgar Latin *melum, from Latin mālum. Compare Aromanian mer, Romansch mail, Friulian mêl.
măr n (plural mere)
From Vulgar Latin *melus, from Latin mālus. Compare Italian melo.
măr m (plural meri)
1) apple tree
The -s for plural is true only for Romlangs above the "LaSpezia-Rimini" line, which means French, Venetian and Castillian to name a few. Under this line the romance languages use the last vowel to tell the number. This is true for Standard Italian, Romanian and Sicilian for exemple.
Sorry, "unul măr" is not correct Romanian.
One apple = un măr
The apple = mărul
"Unui" (masculine/neutral) and "unei" (feminine) are the possessive forms for singular nouns. For example:
maşina unei fete (a girl's car)
maşina unui băiat (a boy's car)
For plural nouns we form the possessive with "unor" regardless of gender:
maşina unor femei = some women's car
maşina unor bărbaţi = some men's car
Unui, unei and unor are possessive indefinite articles. Definite articles are a bit trickier, but indefinite articles are relatively speaking easy.
Măr is a neuter noun, and neuter nouns in Romanian behave like masculine in the singular and feminine in the plural. It seems weird at first, but you get used to it.
Here are some examples of words and their plurals:
un copac, doi copaci (m)
one tree, two trees
un măr, două mere (n)
one apple, two apples
o masă, două mase (f)
one table, two tables
This is specific to neuter nouns, and you won't find a noun that behaves like the reverse.