Το πιστωτικό ίδρυμα ανοίγει καταθετικό λογαριασμό ή λογαριασμό όψεως.

Because ίδρυμα is a neuter noun in Greek. Greek articles must agree with the noun in gender, number, and case.

• το ίδρυμα = the institution
• το πιστωτικό ίδρυμα = the credit institution

The adjective πιστωτικό is also neuter singular, so it matches ίδρυμα.

It is a formal term meaning credit institution or financial institution. In many contexts, it can refer to a bank, but it is slightly broader and more official-sounding than just τράπεζα.

So:

• τράπεζα = bank
• πιστωτικό ίδρυμα = credit institution / banking institution

This kind of wording is common in legal, administrative, and banking language.

Ανοίγει is the present tense, 3rd person singular, from ανοίγω = to open.

Here it does not necessarily mean that the institution is opening an account right now. In formal Greek, the present tense is often used for:

• general statements
• procedures
• legal or official language
• habitual actions

So Το πιστωτικό ίδρυμα ανοίγει... can mean something like:

• The credit institution opens...
• The credit institution opens/provides...
• The credit institution may open... in an institutional/procedural sense

The subject is Το πιστωτικό ίδρυμα and the object is καταθετικό λογαριασμό ή λογαριασμό όψεως.

A useful clue is the case:

• το πιστωτικό ίδρυμα is in the nominative case, so it is the subject
• λογαριασμό is in the accusative case, so it is the direct object

So the structure is:

• [Subject] Το πιστωτικό ίδρυμα
• [Verb] ανοίγει
• [Object] καταθετικό λογαριασμό ή λογαριασμό όψεως

Because λογαριασμό is the accusative singular form, and it is the direct object of ανοίγει.

The basic forms are:

• ο λογαριασμός = the account, account (subject form / nominative)
• τον λογαριασμό = the account (object form / accusative)

In this sentence, the account is what the institution opens, so Greek uses the accusative:

• ανοίγει λογαριασμό = it opens an account

The same is true for καταθετικό λογαριασμό.

Greek often omits the indefinite article in formal or general statements, especially in administrative or institutional language.

So:

• ανοίγει καταθετικό λογαριασμό = opens a deposit account
• ανοίγει έναν καταθετικό λογαριασμό = opens a deposit account

Both are possible, but the version without έναν sounds more formal, generic, or bureaucratic.

The same applies to the second option:

• ή λογαριασμό όψεως
• ή έναν λογαριασμό όψεως

In everyday speech, many speakers would be more likely to include έναν, but in formal text omission is very common.

Because these are two different grammatical patterns.

1. καταθετικό λογαριασμό

Here καταθετικό is an adjective modifying λογαριασμό.

• καταθετικός = deposit-related / depositional
• καταθετικό λογαριασμό = deposit account

The adjective agrees with the noun in case, gender, and number.

2. λογαριασμό όψεως

Here όψεως is not an adjective. It is a genitive form used in a fixed banking expression.

• λογαριασμός όψεως = current account / demand account / checking account

So this second phrase is built as:

• noun + genitive

That is why the word order is different.

It is a formal banking term meaning current account, checking account, or demand account, depending on the variety of English and the banking system.

Literally, it comes from the idea of an account payable at sight or on demand.

So in practical terms:

• λογαριασμός όψεως = checking/current account

This is a fixed term, so learners should treat it as a vocabulary item.

Because όψεως is part of a fixed formal expression. It is an older, more learned genitive form that survives in certain official phrases.

In ordinary Modern Greek, you would usually expect a genitive like όψης, but in banking and legal language, όψεως is standard in this expression:

• λογαριασμός όψεως

So the best approach is not to analyze it as everyday grammar first, but to learn it as a set phrase used in formal Greek.

The sentence is already perfectly natural as it is. Greek often avoids unnecessary repetition when the structure is clear.

Here the two alternatives are:

• καταθετικό λογαριασμό
• λογαριασμό όψεως

Since both are clearly kinds of λογαριασμός, there is no problem. In fact, the noun λογαριασμό does appear in both options:

• καταθετικό λογαριασμό
• λογαριασμό όψεως

What changes is the modifier:

• adjective in the first phrase
• genitive expression in the second phrase

Yes, Greek word order is more flexible than English, because case endings show grammatical function.

The neutral, straightforward order here is:

• Το πιστωτικό ίδρυμα ανοίγει καταθετικό λογαριασμό ή λογαριασμό όψεως.

But other orders are possible for emphasis, especially in speech or stylized writing. For example:

• Καταθετικό λογαριασμό ή λογαριασμό όψεως ανοίγει το πιστωτικό ίδρυμα.

That sounds more marked or emphatic. For learners, the original word order is the safest and most standard.

A more everyday version might use τράπεζα instead of πιστωτικό ίδρυμα, and it might include the indefinite article:

• Η τράπεζα ανοίγει έναν καταθετικό λογαριασμό ή έναν λογαριασμό όψεως.

This is less bureaucratic and more conversational.

So the original sentence sounds like something from:

• a banking form
• terms and conditions
• a legal or official document
• an informational brochure