Si quis falsum iurat, iudex iratus est.

Because after certain little words, especially si (if), Latin regularly uses quis/quid as an indefinite pronoun, not an interrogative one.

So:

• si quis = if anyone
• not if who?

This is a very common Latin pattern. English uses different words, but Latin often does not. A learner should get used to reading quis after si as someone / anyone.

Latin usually prefers quis rather than aliquis after si, and also after a few similar words such as nisi, num, and ne.

So the normal idiom is:

• si quis = if anyone

not usually:

• si aliquis

Both forms are understandable in some contexts, but si quis is the standard textbook pattern.

Iurat is:

• 3rd person singular
• present tense
• active voice
• indicative mood

from the verb iuro, iurare, meaning to swear or to take an oath.

So quis falsum iurat means someone swears something false or more naturally someone swears falsely / commits perjury.

Falsum is a neuter singular accusative form of falsus, -a, -um, meaning false. Here it is being used substantively, meaning something like:

• a false thing
• a false statement
• a lie

So falsum iurat is literally something like he swears a falsehood.

In smoother English, that becomes:

• he swears falsely
• he swears to something false
• he commits perjury

This is a good example of Latin using an adjective as a noun.

Latin sometimes expresses an idea with a noun or substantive adjective where English prefers an adverb.

So instead of saying exactly swears falsely, Latin here says more literally swears something false.

That is perfectly normal Latin idiom. A very literal translation can help you understand the grammar, but the natural English meaning is still swears falsely.

That is a very common question.

Here iratus is functioning like an adjective meaning angry, and est means is. So:

• iudex iratus est = the judge is angry

It may look a little like a perfect tense form, because Latin often uses a participle plus est. But in this sentence the most natural sense is simply a state: the judge is angry.

Also notice the agreement:

• iudex is singular nominative
• iratus is singular nominative masculine

So iratus matches iudex.

This is a simple present condition:

• Si quis falsum iurat, iudex iratus est.

Both verbs are in the present indicative, which gives a straightforward sense such as:

• If anyone swears falsely, the judge is angry
• If anyone swears falsely, the judge gets angry

Depending on context, it can sound like:

• a general rule
• a habitual truth
• a real possibility

It is not a contrary-to-fact condition like if anyone had sworn falsely...

Not really. Latin word order is much freer than English word order because the endings show how words function.

Here the sentence is arranged in a very natural way:

• Si quis falsum iurat = the if clause first
• iudex iratus est = the main clause second

That is probably the clearest order for this sentence.

Latin could rearrange the words for emphasis, for example:

• Iudex iratus est, si quis falsum iurat

and the basic meaning would stay the same. But the given order is probably the most straightforward.

In this sentence, yes, iratus is masculine, so it suggests a male judge.

If the judge were female, Latin would normally say:

• iudex irata est

The noun iudex itself can refer to a judge of either sex, but the adjective tells you the gender intended in the sentence.

No. Here iurare means to swear an oath, not to curse or to use swear words.

So falsum iurat is about making a false sworn statement, not about rude language. In legal or moral context, it is essentially perjury or swearing falsely.