הקוד הסודי הוא לא קוד חד-פעמי.

Because ה־ means the.

• קוד סודי = a secret code
• הקוד הסודי = the secret code

Both words take ה־ because the whole noun phrase is definite:

• הקוד = the code
• הסודי = the secret

In Hebrew, when an adjective describes a definite noun, the adjective usually becomes definite too.

הוא here functions like is in English.

So:

• הקוד הסודי = the secret code
• הוא = is
• לא קוד חד-פעמי = not a one-time code

In present-tense Hebrew, sentences with to be often do not use a verb, especially with adjectives or locations. But when two noun phrases are being linked, Hebrew often uses a pronoun like הוא to connect them.

So this structure is very natural:

• X הוא Y
• X is Y

Here:

• הקוד הסודי הוא לא קוד חד-פעמי
• The secret code is not a one-time code

לא means not, and it negates what follows.

Here it negates the noun phrase קוד חד-פעמי:

• לא קוד חד-פעמי = not a one-time code

So the sentence literally works like:

• The secret code is not [a one-time code].

This is the normal way to make this kind of sentence negative in Hebrew.

חד-פעמי means one-time, single-use, or for one occasion only, depending on context.

It is built from:

• חד = one / single
• פעם = time / occasion

So the basic idea is used only once.

In modern Hebrew, חד-פעמי is very common. For example:

• כלים חד-פעמיים = disposable utensils
• קוד חד-פעמי = one-time code
• אירוע חד-פעמי = a one-time event

Because it is a compound adjective made from two parts: חד + פעמי.

Hebrew often uses a hyphen in compounds like this, especially in careful or standard writing. In everyday informal writing, you may sometimes see variation, but חד-פעמי is the standard written form.

So you should learn it as one unit of meaning:

• חד-פעמי = one-time / disposable / single-use

Good question — both are possible, but they are not exactly the same.

1. הקוד הסודי הוא לא קוד חד-פעמי

   • literally: The secret code is not a one-time code
   • This compares one type of code to another type of code.

2. הקוד הסודי הוא לא חד-פעמי

   • literally: The secret code is not one-time
   • This describes the code with an adjective.

Both are grammatical. The version with repeated קוד is a little more explicit and classification-like: it says this code does not belong to the category of one-time codes.

It is an adjective.

• סוד = secret as a noun
• סודי = secret / confidential as an adjective

So:

• קוד סודי = secret code
• literally: code secret

The adjective סודי agrees with קוד in gender, number, and definiteness.

Since קוד is masculine singular, סודי is also masculine singular.

Because Hebrew adjectives agree with the nouns they describe.

Here:

• קוד is masculine singular
• so the adjective is masculine singular: סודי

If the noun were feminine singular, the adjective would usually look different. For example:

• שיטה סודית = a secret method

And for a definite noun phrase:

• הקוד הסודי = the secret code
• השיטה הסודית = the secret method

So agreement is an important pattern to notice.

A natural pronunciation is:

ha-kod ha-so-di hu lo kod khad-pa-a-mi

More smoothly: hakod hasodí hu lo kod khad-pa'amí

A few pronunciation notes:

• הקוד = ha-KOD
• הסודי = ha-so-DI
• הוא = hu
• לא = lo
• חד-פעמי = khad-pa-a-MI or khad-pa'amí

The sound ח in חד is the throaty Hebrew kh sound, not an English h.

Not always, but in this sentence it is the normal choice.

Hebrew often omits is/are in present tense when using adjectives:

• הקוד הסודי חדש = The secret code is new

But when linking one noun phrase to another noun phrase, Hebrew commonly uses הוא:

• דני הוא מורה = Danny is a teacher
• זה הוא הפתרון = This is the solution
• הקוד הסודי הוא לא קוד חד-פעמי = The secret code is not a one-time code

So here הוא helps clearly connect the secret code with not a one-time code.

Yes, in more formal Hebrew you might see אינו.

For example:

• הקוד הסודי אינו קוד חד-פעמי

This means the same thing: The secret code is not a one-time code.

The difference is mostly style:

• הוא לא = common, everyday, conversational
• אינו = more formal, written, or elevated

For most learners, הוא לא is the more useful pattern to recognize first.