Learn Hardcore German: Im Anzug fühlt sie sich stark und professionell. - In the suit she feels strong and professional.

Both im Anzug and in dem Anzug are grammatically correct, but in normal spoken and written German the contracted form im is strongly preferred unless you want to emphasize dem for contrast.

Why is it im Anzug (dative) and not in den Anzug (accusative)?

The preposition in can take either dative or accusative, depending on the meaning:

Dative → location / state (where?):
Sie ist im Anzug. = She is in the suit.
Accusative → movement / change of location (where to?):
Sie geht in den Anzug. = She goes into the suit. (i.e. she’s putting it on)

In Im Anzug fühlt sie sich …, the suit is just the situation / state she is in, not the goal of a movement, so German uses the dative: im (in dem) Anzug.

Why does the sentence start with Im Anzug and not with Sie?

German word order follows the verb‑second rule in main clauses:

The conjugated verb must be in second position.
The first position can be almost anything: subject, time expression, place, etc.

So both are possible:

Im Anzug fühlt sie sich stark und professionell.
(First: Im Anzug, second: fühlt)
Sie fühlt sich im Anzug stark und professionell.
(First: Sie, second: fühlt)

The version with Im Anzug first puts more emphasis on the situation “in a suit”. The version starting with Sie is more neutral and is probably the most typical “default” order.

What is the function of sich in fühlt sie sich? Why can’t we just say fühlt sie stark?

fühlen can be used in two main ways:

Transitive (with a direct object)
- Ich fühle den Stoff. = I feel the fabric.
  Here you can’t add adjectives like strong, professional directly.
Reflexive: sich fühlen + adjective
- Sie fühlt sich stark. = She feels strong.

In your sentence, fühlen is used reflexively, so the reflexive pronoun sich is required:

fühlt sie sich stark und professionell = she feels strong and professional

Without sich, the sentence would be ungrammatical in this meaning.

Why is the reflexive pronoun sich and not sie or something else?

Reflexive pronouns in German depend on person and case, not on grammatical gender. For the 3rd person singular (he, she, it) in the accusative, the reflexive pronoun is always sich:

Er fühlt sich gut. – He feels good.
Sie fühlt sich gut. – She feels good.
Es fühlt sich gut an. – It feels good.

So with sie as subject (she), the reflexive pronoun must be sich, not sie.

Why are the adjectives stark and professionell not inflected (no endings like -e or -en)?

German distinguishes two main uses of adjectives:

Attributive (before a noun, with endings):
- ein starker, professioneller Auftritt – a strong, professional appearance
  (Adjectives come before the noun and get endings: stark-er, professionell-er.)
Predicative (after verbs like sein, werden, bleiben, fühlen, etc., with no endings):
- Sie fühlt sich stark und professionell.
- Sie ist stark und professionell.

In your sentence, stark and professionell are predicative adjectives describing how she feels, so they do not take endings.

Can we say Sie fühlt sich im Anzug stark und professionell instead? Does it change the meaning?

Yes, that’s fully correct:

Sie fühlt sich im Anzug stark und professionell.

The meaning is essentially the same. The difference is in emphasis / information structure:

Im Anzug fühlt sie sich stark und professionell.
Emphasizes the condition “in a suit”; often used when contrasting with other situations (e.g. In casual clothes she feels insecure, but in a suit she feels strong…).
Sie fühlt sich im Anzug stark und professionell.
More neutral subject‑first order; just reports how she feels in that situation.

Both follow the verb‑second rule and are natural.

Why is it Anzug and not a special word for a woman’s suit?

In modern German, der Anzug is a fairly general word for a (business) suit, regardless of the wearer’s gender. A woman wearing a suit is also said to be im Anzug.

There is also das Kostüm, traditionally used for a women’s skirt‑suit, but:

Im Anzug works absolutely fine for a woman in a (pants) suit.
The sentence focuses on the feeling (strong, professional), not on a gendered clothing term.

So Im Anzug is normal and idiomatic even when talking about a woman.

Why is it Im Anzug and not In einem Anzug? Is that also possible?

Both are possible, but they feel slightly different:

Im Anzug fühlt sie sich stark und professionell.
→ Literally: “In the suit…” but idiomatically often more general: in a suit / when she wears a suit.
It can refer to a specific suit or to wearing suits as a style.
In einem Anzug fühlt sie sich stark und professionell.
→ Stresses “in a suit (one suit, not specified)”.
Sounds more like you’re contrasting with other types of clothing on one particular occasion.

In many contexts, im Anzug is used generically, almost like “in a suit / in suits”.

Why is the verb form fühlt and not fühlen?

fühlt is the 3rd person singular present tense of fühlen:

ich fühle
du fühlst
er/sie/es fühlt
wir fühlen
ihr fühlt
sie fühlen

Because the subject is sie (she, singular), the correct present tense form is fühlt, not fühlen.

Do we need a comma before und in stark und professionell?

No. When you simply link two adjectives with und that describe the same thing, there is no comma:

stark und professionell
groß und freundlich
langsam und vorsichtig

A comma would only appear if you had more complex structures (e.g. a whole clause after und), which is not the case here.

Is there any difference between Sie fühlt sich stark und professionell and Sie ist stark und professionell?

Yes, there is a nuance:

Sie fühlt sich stark und professionell.
Focuses on her subjective feeling in that moment or in that situation (here: when she is in a suit).
Sie ist stark und professionell.
States her qualities as facts – she is strong and professional (more objective description of her character or abilities).

In the original sentence, fühlt sich is used because the suit influences how she feels about herself.