"A bright shirt."
Firstly, please join me in telling Duolingo that they should show (on the hints) whether a noun is masculine or feminine - it's vital!!! Secondly, here's what I've picked up (disclaimer: I am also a beginner, so it may be my misconception):
Generally, a noun that ends in a broad consonant is m., whereas a noun that ends in a slender consonant is f..
exceptions: - f. óg/-eog (broad) - m. -óir/-eoir (slender) - m. diminutive -ín
That really isn't a rule for recognizing whether nouns are masculine or feminine.
There are 14 words that start with lé and end in e in the FGB. 3 of the 14 are simple feminine nouns. 1 is a simple masculine noun. 3 are compound words, which take their gender from the last of the compounding words - 1 of these has a feminine last part, 2 have masculine last parts. 1 is the plural of a masculine noun, 1 is the genitive of a masculine noun, 2 are the genitives of feminine nouns, 1 is a variant spelling of a feminine noun that doesn't match this "rule", and two are variant spellings of adjectives.
There is a "rule" (rule-of-thumb is more appropriate) that says that "abstract nouns ending in e" are usually 4th declension feminine nouns, which accounts for léithe - "greyness" and léire - "clearness". But léine clearly isn't an abstract noun, and the "rule" is that nouns that end in a vowel that aren't abstract are usually 4th declension masculine nouns.
leasaithe - plural of a masculine noun
leaslíne - feminine, but a compound word
leaspaire - masculine
leiche - genitive of a feminine noun
leicthe - variant spelling of an adjective
leige - variant spellings of feminine nouns
leigthe - variant spelling of an adjective
leire - feminine
leiroidhre - masculine, but a compound word
leise - genitive of a feminine noun
leite - genitive of a masculine noun
leithe - feminine
leithuisce - masculine, but a compound word
I'm relatively new to Duolingo, so maybe I'm missing a resource, but it would be very helpful if a word bank was provided in the Tips section of each new lesson showing the roots of verbs and m/f for nouns (and any other pertinent exceptions or unique attributes of new words being introduced). I struggle to put together my own notes for each section based on the few words listed in Tips, then the bit by bit definitions gleaned from each lesson, but it makes it very difficult to start applying the rules introduced, that rely on my knowing the gender of a noun, or the root of a verb to tell if it is a 1st or 2nd conjugation, when I haven't been provided that information. I am picking things up as I stick with the course, but I see others struggling for the same reason in comments going back several years. I do find the Memrise reviews help, but their word banks are not identical. Is there a word bank somewhere for this course that I am missing?
Are you using this
Memrise course? It is fairly close to what is in Duolingo.
Sorcha is a fairly common name in Scotland too among Gaelic speakers, and is still used as an adjective in Gàidhlig for "bright" or "clear" (hence why the name Sorcha is often Anglicized as "Claire" or "Clara"), although "soilleir" seems more commonly used nowadays. If I ever change my name to something genuinely Gaelic I'd go with Sorcha. It's so very Gaelic-y.