One stem noun

By far we have studied noun and its stems too. But one thing that makes noun difficult to understand is that it uses multiple stems according to the vowel and the form. As we know that there are 3 noun stems, so let us begin with the first one.

One stem noun

Talking about these noun stems, one thing is quite common about them. All of their one stems noun are used in front of the vowel in every situation. However, that is not the case with the second stem. The second stem is a more complex one because of the involvement of sandhi, which we will learn further

 वाच् + अम् → वाचम्
vāc + am → vācam
Speech (case 2 singular)

वाच् → वाक्
vāc → vāk
Speech (case 1 singular)

Now let us see this team in the neuter form in all the identical cases.

(Neuter consonant stem)

The noun may seem irregular because of regular sandhi changes, also there is nasal sound in case 1, 2, and 8.

External sandhi

External sandhi applicable to one stem noun has some common rules;
• The final sound of the word will be similar to the original sound
• If the original sound has a nasal the final sound will automatically become nasal

(Speech is a goddess).
वाक् देवी –> वाग् देवी
vāg devī –> vāk devī

(Speech itself)
वाक् एव –> वाग् एव
vāk eva –> vāg eva

(Not speech)
वाक् न –> वाङ् न
vāk na –> vāṅ na

Note that k and n have the same point of pronunciation.

Another rule of sandhi is that when followed by h sound, t becomes d and h becomes dh

वाक् हि तस्मिन् भवति → वाग् घि तस्मिन् भवति
vāk hi tasmin bhavati → vāg ghi tasmin bhavati
For speech is in him.