Felmosóronggyal felmosom a vizet.

It is a compound noun plus a case ending:

• felmosó = mopping / for mopping / mop-
• rongy = rag, cloth
• -val / -vel = with

So felmosórongy is literally mop-cloth / cleaning rag, and felmosóronggyal means with a mop cloth.

Hungarian writes compounds together much more often than English does, so a form like felmosórongy as one word is completely normal.

Because the suffix -val / -vel often changes shape after a consonant.

With many consonant-final words, the v of -val/-vel assimilates to the final consonant of the word, and that consonant is written doubled. So:

• rongy + val → ronggyal

This is a very common pattern in Hungarian:

• kéz + vel → kézzel
• ház + val → házzal
• bor + val → borral

So ronggyal is exactly what you should expect here.

Because Hungarian often leaves out the indefinite article egy when the meaning is general or non-specific, especially with tools or means.

So:

• Felmosóronggyal = with a mop cloth / using a mop cloth
• Egy felmosóronggyal = with one/a mop cloth with more emphasis on one
• A felmosóronggyal = with the mop cloth, referring to a specific one

In this sentence, the tool is just being mentioned as the means, so no article is very natural.

It can be analyzed as:

• fel- = a verbal prefix
• mos = wash
• -om = I with a definite object in the present tense

So felmosom is roughly I mop it up / I wash it up.

In real Hungarian, felmos is a normal verb meaning to mop up / to wet-mop, so learners should think of felmosom as a whole verb form, not only as a literal combination of parts.

Literally, fel often means up, but in verbs it can also give a more completed, directional, or result-focused meaning.

With mos (to wash), the prefixed verb felmos means something like:

• to mop up
• to wet-mop
• to clean by mopping

So the prefix is part of the normal dictionary form of the verb here. It is not just a separate word meaning up in a simple English-like way.

Because the sentence has a definite direct object: a vizet (the water).

Hungarian verbs have two main present-tense conjugations:

• indefinite conjugation: used when there is no object, or the object is indefinite
• definite conjugation: used when the object is definite

So:

• felmosok = I mop / I am mopping or I mop something in a non-definite sense
• felmosom a vizet = I mop up the water with a definite object

That is why -om appears here.

Here -om marks:

• 1st person singular = I
• present tense
• definite conjugation

So felmosom means not just I mop, but specifically I mop it / I mop the definite thing.

This is one of the features English speakers usually need time to get used to, because English does not change the verb this way depending on whether the object is definite.

Because vizet is the direct object of the verb, and Hungarian marks direct objects with the accusative ending, usually -t.

So:

• víz = water
• a víz = the water as a subject/basic form
• a vizet = the water as a direct object

The article is a because víz begins with a consonant sound (v). Hungarian uses:

• a before consonant sounds
• az before vowel sounds

So a vizet is exactly right.

Because víz has a changed stem in suffixed forms: viz-.

So when Hungarian adds the accusative ending, it does not produce vízt. Instead it uses the stem viz- and adds a linking vowel plus -t:

• víz → vizet

This is not unique to this word; some Hungarian nouns have stem changes when endings are added. It is best learned as part of the noun's pattern:

• víz
• vizet
• vizes

Because Hungarian word order is much freer than English word order, and it often shows topic and focus rather than basic grammatical roles.

In this sentence, Felmosóronggyal comes first because the speaker is setting the scene with the instrument/tool:

• Using a mop cloth, I mop up the water

The cases and verb form already show what the parts are doing, so Hungarian can move things around more easily than English.

Other orders are possible, but the emphasis changes. For example:

• Felmosom a vizet felmosóronggyal. = more neutral flow, with the tool added later
• A vizet mosom fel... = stronger focus on the water

So the given order is not random; it reflects information structure.

In a neutral declarative sentence, the verbal prefix usually stays attached to the verb:

• felmosom

But in Hungarian, prefixes often move away from the verb when there is:

• negation
• strong focus
• certain question structures

For example:

• Nem mosom fel a vizet. = I am not mopping up the water.
• A vizet mosom fel. = It is the water that I mop up.

So in your sentence, the prefix stays attached because the sentence is a straightforward statement with no special focus immediately before the verb.

Two important pronunciation points:

• Hungarian s is pronounced like English sh
• Hungarian gy is a soft consonant sound with no exact English equivalent, somewhat like a very soft dy

So in this sentence:

• felmosó has s = sh
• ronggyal contains a doubled gy sound because of the suffix assimilation

A practical learner-friendly approximation is:

• felmosó ≈ fel-mo-sho
• gy ≈ a soft dy

It is not a perfect English match, but that approximation is good enough to start with.