it letters

Before we talk about it letters, let's first understand one of the problems that Pāṇini was facing. Since we are not ancient grammarians, let's put the problem in simple and concrete terms.

Suppose we run a clothing store that sells all kinds of shirts and saris. And when our customers arrive, they want to find exactly what they're looking for. How might we organize this store?

One obvious idea is to group similar items together: shirts with shirts, large items with large items, and so on. Pāṇini uses a similar device to organize lists of verb roots, lists of pronouns, and various other terms.

But one problem with this approach is that there is a limit to how much information it can easily convey. For example, which shirts must be washed in cold water? Which have been imported? Which are on sale? It can be difficult to manage all of these different groupings.

One elegant solution is to add a paper tag to each item we sell. This small tag can tell us about the price, the country of origin, and whatever other information we need to know. The tag is not part of the shirt; it's just a label that tells us what the shirt is like.

Pāṇini probably didn't run a clothing store, but he certainly faced a similar problem. He wanted to organize all of the terms in Sanskrit grammar so that their roles and functions were clear. Most of these terms are grouped in large lists, just as we might group shirts together in our store. But there are too many important properties that need to be conveyed. Some of these properties are:

  • whether certain verbs are allowed specific suffixes

  • whether certain suffixes cause any unusual sound changes

  • whether certain terms have any unusual accents

Just as we might add tags to items in our store, Pāṇini adds tags to the different terms in the grammar. These tags are not part of the terms they attach to; they're just labels that tell us what the term is like.

And since the Aṣṭādhyāyī is part of an oral tradition, it's only fitting that these tags are other sounds. The technical term for these sounds is it.

In eight rules, Pāṇini defines which sounds are it and which are not. These rules are so critical to the rest of the grammar that we will list all eight of them here. If you know some Sanskrit, we recommend memorizing them.

Nasal vowels

  • उपदेशे ऽजनुनासिक इत्। १.३.२
    upadeśe 'janunāsika it (1.3.2)
    upadeśe ac anunāsikaḥ it
    In upadeśa, nasal vowels are [called] it.

The term upadeśa (“instruction, teaching”) here refers to the teaching context of vyākaraṇa and the Pāṇinian system. Specifically, it refers to the technical language used within the system. So within this technical context, nasal vowels are called it.

With this rule, we can better understand the term udit that was used in the previous lesson. For example, we learned previously that ku refers to the five sounds ka, kha, ga, gha, and ṅa. More properly, this is ku̐ with a nasal vowel.

By rule 1.3.2, ku̐ is the consonant k with the vowel u as an it. By rule 1.1.70, the short vowel u is called ut. So, we can say that k is udit (ut-it, “having u as an it”). And since k is udit, it is in scope for rule 1.1.69 (aṇudit savarṇasya cāpratyayaḥ), which lets us concisely refer to savarṇa (similar) sounds.

Final consonants

  • हलन्त्यम्। १.३.३
    halantyam (1.3.3)
    hal antyam
    Final consonants [are called it in upadeśa].

With this rule, we can better understand the terms from the Shiva Sutras. In the term ac, for example, the final c is an it sound. Then we can apply rule 1.1.71, which we haven't seen yet. First, we bring in rule 1.1.68 for context:

  • स्वं रूपं शब्दस्याशब्दसंज्ञा। १.१.६८
    svaṃ rūpaṃ śabdasyāśabdasaṃjñā (1.1.68)
    svam rūpam śabdasya a-śabda-saṃjñā
    A word [denotes] its own form if it is not a definition (saṃjñā).

Then, we can define rule 1.1.71:

  • आदिरन्त्येन सहेता। १.१.७१
    ādirantyena sahetā (1.1.71)
    ādiḥ antyena saha itā
    An initial [item denotes its own form and intermediates] up to the final it.

Rule 1.1.71 defines the basic mechanism of the Shiva Sutras: an initial term is paired with an it and includes all of the terms between them:

  • ण् → अ इ उ
    a → a i u

  • क् → इ उ ऋ ऌ
    ik → i u ṛ ḷ

Terms that follow this mechanism are called pratyāhāras, and we will see more of them in later lessons.

Minor rules

For our current needs, the next five rules are minor, and we've left only minor comments on them. Notice the context that carries over from one rule to the next. The order of rules here is not arbitrary; it is arranged to express as much as possible in as little space as possible.

  • न विभक्तौ तुस्माः। १.३.४
    na vibhaktau tusmāḥ (1.3.4)
    na vibhaktau tu-s-māḥ
    The tu sounds, s, and m are not [called it in upadeśa] when they are in a vibhakti (nominal case ending).

This rule applies to the inflectional endings that appear at the end of nominal stems. It will be useful later, but not right now.

  • आदिर्ञिटुडवः। १.३.५
    ādirñiṭuḍavaḥ (1.3.5)
    ādiḥ ñi-ṭu-ḍavaḥ
    Initial ñi̐, ṭu̐, and ḍu̐ [are called it in upadeśa].

These rules are mainly found on verb roots and usually allow specific suffixes. The new word ādiḥ (“initial”) cancels the force of na (“not”) from rule 1.3.4.

  • षः प्रत्ययस्य। १.३.६
    ṣaḥ pratyayasya (1.3.6)
    ṣaḥ pratyayasya
    The [initial] of a pratyaya (suffix) [is called it in upadeśa].

Much of the Aṣṭādhyāyī focuses on pratyayas and their properties. We will explore the various pratyayas later on.

  • चुटू। १.३.७
    cuṭū (1.3.7)
    The [initial] cu sounds and ṭu sounds [of a pratyaya are called it in upadeśa].

cu̐ refers to the five sounds ca, cha, ja, jha, and ña, and likewise for ṭu̐. For the interpretation of ṭu̐, see our note above on rule 1.3.5.

  • लशक्वतद्धिते। १.३.८
    laśakvataddhite (1.3.8)
    la-śa-ku a-taddhite
    The [initial] l, ś, and the ku sounds [of a pratyaya are called it in upadeśa] when not in a taddhita (nominal suffix).

A taddhita suffix is used to create nominal stems. We will revisit this rule later.


Finally, we see what happens to these it letters:

  • तस्य लोपः। १.३.९
    tasya lopaḥ (1.3.9)
    tasya lopaḥ
    That [i.e. any it letter] undergoes lopa.

And what is lopa?

  • अदर्शनं लोपः। १.१.६०
    adarśanaṃ lopaḥ (1.1.60)
    a-darśanam lopaḥ
    Disappearance is [called] lopa.

Rule 1.3.9 emphasizes a simple fact: these it letters are just a helpful notation. They are not “real” Sanskrit and have no meaning outside the technical world of the Pāṇinian system. In our clothing store, a tag's role is to tell us something about the clothes it is attached to; and in the world of grammar, an it letter's role is to tell us something about the terms it attaches to.


With the rules above, we have cleaned up some of the loose ends that earlier lessons left behind. We now have a complete and compact system for defining different groups of Sanskrit sounds.

With this system in hand, we can now turn to the task of using it. In the next lesson, we will see how this system can model sandhi changes clearly and concisely. We will also learn about substitution rules, which are the last major piece of the system's formal language.