Questions & Answers about O lago é fundo.
O is the masculine singular definite article, equivalent to “the” in English.
- O lago = the lake (a specific lake that both speakers know about).
- In Portuguese, you normally cannot drop the article the way you sometimes can in English. You usually must say O lago, not just Lago, when you’re talking about a particular lake.
- For a non‑specific lake you would use the indefinite article: Um lago = a lake.
Both é and está mean “is”, but they come from different verbs:
- é = 3rd person singular of ser (used for more permanent or inherent characteristics)
- está = 3rd person singular of estar (used for temporary states, locations, changing conditions)
In O lago é fundo, being deep is treated as a permanent or defining characteristic of that lake, so you use ser:
- O lago é fundo. = The lake is deep (that’s the kind of lake it is).
Using O lago está fundo would sound unusual; you might only hear it in very specific, metaphorical, or joking contexts. For describing the normal depth of a lake, use é.
In Portuguese, most descriptive adjectives normally come after the noun:
- O lago fundo (or, more naturally, O lago é fundo) = The deep lake / The lake is deep.
Putting fundo before the noun (O fundo lago) is not standard in this meaning; it sounds wrong or at best poetic/odd.
Some adjectives can come before the noun (and sometimes change meaning when they do), but fundo as “deep” in this kind of sentence should follow the noun or the verb:
- O lago é fundo. ✅
- O lago fundo. (possible in some contexts, more like “the deep lake”, but less common as a standalone sentence)
- O fundo lago. ❌ (not used in normal speech)
Adjectives in Portuguese must agree in gender (masculine/feminine) and number (singular/plural) with the noun.
Base form (masculine singular): fundo
Masculine singular:
- O lago é fundo. – The lake is deep.
Feminine singular:
- A piscina é funda. – The swimming pool is deep.
- A lagoa é funda. – The pond/lagoon is deep.
Masculine plural:
- Os lagos são fundos. – The lakes are deep.
Feminine plural:
- As piscinas são fundas. – The swimming pools are deep.
Pattern:
- -o → -a for feminine
- Add -s for plural: fundo, funda, fundos, fundas
Both can mean “deep”, and there is overlap, but there are tendencies:
fundo
- Very common, everyday word.
- Used for physical depth: lakes, wells, holes, swimming pools, etc.
- O lago é fundo. – The lake is deep.
- Um poço muito fundo. – A very deep well.
profundo
- Slightly more formal or “literary”.
- Also used for abstract or emotional depth:
- um sono profundo – a deep sleep
- tristeza profunda – deep sadness
- silêncio profundo – deep silence
- Can also be used for physical depth, but less colloquial.
In everyday speech about a lake, fundo is the most natural choice.
Yes, fundo can be both an adjective and a noun.
Adjective – “deep”
- O lago é fundo. – The lake is deep.
Noun – “bottom”, “back”, “background”, “rear”
- o fundo do lago – the bottom of the lake
- o fundo da gaveta – the back/bottom of the drawer
- no fundo da sala – at the back of the room
- fundo musical – background music
So context tells you whether fundo is “deep” or “bottom/back/background”.
In European Portuguese:
- O – [u] (like the oo in “food”, but shorter)
- lago – LA-go:
- la like “la” in “lava”
- go like “go” but with a shorter o
- é – [ɛ] (like e in “bet”, but a bit more open)
- fundo – FUN-do:
- fu roughly like English foon but with a shorter vowel
- n is clear
- do with a short o, closer to do in “dot” but less open
Word stress: LA-go, FUN-do (stress on the first syllable of each).
So roughly: [u 'la.gu ɛ 'fũ.du], with the un in fundo nasalized in typical European pronunciation.
Yes, lago is masculine, which is why we say o lago, not a lago.
A common rule of thumb (with exceptions):
Nouns ending in -o are usually masculine:
- o lago (lake)
- o carro (car)
- o livro (book)
Nouns ending in -a are usually feminine:
- a lagoa (pond/lagoon)
- a casa (house)
- a mesa (table)
There are exceptions (e.g. a mão, o mapa), so you gradually learn the gender with each noun. But for lago, masculine is standard: o lago é fundo.
For a normal full sentence, no. You need a form of ser or estar:
- O lago é fundo. – correct full sentence
- O lago fundo. – could appear as a noun phrase (“the deep lake”) in some contexts, but it is not a complete normal sentence in Portuguese.
So if you want to say “The lake is deep”, you must include é.
You can use intensifiers like muito or mesmo:
- O lago é muito fundo. – The lake is very deep.
- O lago é mesmo fundo. – The lake is really deep / It’s indeed deep. (European Portuguese usage)
You can also combine them for emphasis in speech:
- O lago é mesmo muito fundo. – The lake is really very deep.
You need to change the verb and the adjective for number and add não for negation.
The lakes are deep.
- Os lagos são fundos.
- os = plural of o
- são = plural of é
- fundos = plural of fundo
The lake is not deep.
- O lago não é fundo.
- não goes before the verb é.
Yes, if the context makes it clear you’re referring back to o lago:
- O lago é fundo. Ele é fundo. – The lake is deep. It is deep.
Notes:
- Ele is the masculine singular pronoun (“he / it”). Since lago is masculine, you use ele.
- In real conversations, you’d normally say one or the other, not both together.
- Using just É fundo. without ele would also be possible if the subject is very clear from context, but as a neutral full sentence with a pronoun you’d say Ele é fundo.
Both are correct but slightly different:
O lago é fundo. – The lake is deep.
- Refers to a specific lake both speakers know from context.
Este lago é fundo. – This lake is deep.
- este = this (near the speaker).
- Often used when you are close to or pointing at the lake.
So o lago is “the lake” in general context; este lago is “this lake” in a more situational, deictic way.