Also known as: the infinitive, tumun

In this lesson, we will learn about the root suffix -tum, which creates uninflected words.

When added to some root that means “X,” -tum creates a word that means “to X.” Here are some examples:

  • अहं खादितुम् इच्छामि।
    ahaṃ khāditum icchāmi.
    I want to eat.

  • एतान् न हन्तुम् इच्छामि।
    etān na hantum icchāmi.
    I don't want to kill them.
    (Bhagavad Gita 1.34)

We almost always use -tum with another verb. Often, we use -tum words to express that someone wants to do something:

  • गजः खादितुम् इच्छति।
    gajaḥ khāditum icchati.
    The elephant wants to eat.

But there are many other verbs that we can use with -tum:

  • गजः खादितुं शक्नोति
    gajaḥ khādituṃ śaknoti.
    The elephant is able to eat.

  • गजः खादितुं जानाति
    gajaḥ khādituṃ jānāti.
    The elephant knows (how) to eat.

  • गजः खादितुम् आरभते
    gajaḥ khāditum ārabhate.
    The elephant begins to eat.

  • गजः खादितुं यतते
    gajaḥ khādituṃ yatate.
    The elephant tries to eat.

  • गजः खादितुम् अर्हति
    gajaḥ khāditum arhati.
    The elephant deserves to eat.

And in a more general way, -tum can show the reason that some action was done:

  • गजः खादितुं चरति।
    gajaḥ khādituṃ carati.
    The elephant walks (in order) to eat.

  • गजः खादितुं धावति।
    gajaḥ khādituṃ dhāvati.
    The elephant runs (in order) to eat.

Sound changes

When we add -tum, we strengthen the root's vowel to the medium level. As usual, some roots don't use iṭ:

  • नी → नेतुम्
    nī → netum
    lead → to lead

and others do:

  • वन्द् → वन्दितुम्
    vand → vanditum
    venerate → to venerate

Otherwise, -tum generally causes similar sound changes to -tvā:

  • बुध् → बोद्धुम्
    budh → boddhum
    awaken → to awaken

  • मुच् → मोक्तुम्
    muc → moktum
    free → to free

  • गै → गातुम्
    gai → gātum
    sing → to sing


-tum is a common suffix that is worth knowing well.