Enigma este dificilă.

The base form is enigmă. In this sentence, enigma is the definite singular form, meaning the enigma.

Romanian usually puts the definite article at the end of the noun instead of using a separate word like English the.

• o enigmă = an enigma
• enigma = the enigma

For many feminine nouns that end in -ă, the singular definite form is made by changing that final -ă to -a.

So:

• enigmă → enigma

This is a normal grammatical change, not a different word.

Romanian nouns have grammatical gender, and enigmă is a feminine noun.

You can tell from forms like:

• o enigmă — the feminine form of a/an
• enigma dificilă — the adjective is also feminine

Also, many Romanian nouns ending in -ă are feminine, though that is a pattern, not an absolute rule.

Because Romanian adjectives must agree with the noun they describe in gender and number.

Since enigma is feminine singular, the adjective also has to be feminine singular:

• dificil = masculine/neuter singular
• dificilă = feminine singular

So Enigma este dificilă is the correct agreement.

Este is the 3rd person singular present form of a fi, which means to be.

So este means is.

• Enigma este dificilă = The enigma is difficult

In everyday speech, Romanians very often use the shorter form e:

• Enigma e dificilă.

Both are correct.

Usually no. In a normal sentence like this, Romanian keeps the verb a fi.

So:

• Enigma este dificilă. = correct
• Enigma dificilă. = not a normal complete sentence in standard Romanian

This is different from some languages where the present-tense is can be left out.

Normally, no.

Because enigma is the definite form, the sentence is understood as the enigma is difficult, not an enigma is difficult.

If you wanted an enigma, you would use:

• o enigmă

So the indefinite version would be:

• O enigmă este dificilă.

The most neutral and standard order is:

• Enigma este dificilă.

That is basically Subject + is + adjective.

Romanian word order is somewhat flexible, so different orders are possible for emphasis or style, but the given sentence is the normal, straightforward one.

A useful approximate pronunciation is:

eh-NEEG-ma YES-te dee-fee-CHEE-luh

A few details:

• enigma: the g is a hard g, like in go
• este: at the beginning of a word, e is often pronounced like ye, so it sounds like YES-te
• dificilă: ci sounds like ch
• final ă is a short neutral vowel, similar to the a in sofa

The main stress is roughly:

• e-NIG-ma
• ES-te
• di-fi-CI-lă

No. It is capitalized here only because it is the first word of the sentence.

In the middle of a sentence, it would normally be written enigma, unless it were actually being used as a title or name.