With regard to vows, follow the colloquial language-בִנְדָרִים הַלֵּךְ אַחַר לְשׁוֹן בְּנֵי אָדָם. TB Nedarim 30

 We have seen through our journey at the Gemara always likes to bring proof texts from verses in the Bible. Today's daf T B Nedarim 30 teaches us the exception to that proclivity. The mishnayot on this daf examine sets and subsets when it comes to vows. When a person vows not to benefit from a subset, he may benefit from the larger set. However, when a person vows not to benefit from the larger set, the subset is included in this vow. Here is one example from our daf.

"One who takes a vow not to derive benefit from those that are born [yeludim] is permitted to derive benefit from those who will be born [noladim] after the time of the vow. But if one takes a vow not to derive benefit from those who will be born, he is also prohibited from deriving benefit from those that are already born at the time of the vow." (Sefaria.org translation) 

Rav Pappa and Abaye cite different versus to prove whether noladim means those who will be born or those who are already born. "With regard to the distinction between the terms in the mishna, Rav Pappa said to Abaye: Is this to say that the word noladim means those who will be born in the future? But if that is so, it says in the verse: “Your two sons who were born [noladim] to you in the land of Egypt” (Genesis 48:5), does it also mean those who will be born? The verse is referring to Manasseh and Ephraim, who were already alive. 

"The Gemara responds: But rather, what should one say; that the expression means those already born? However, if that is so, that which is written: “Behold, a son shall be born [nolad] to the house of David, Josiah by name” (I Kings 13:2), is the meaning also that he is already born? But Manasseh had not yet come into this world, and certainly not his grandson Josiah." (Sefaria.org translation) 

The Gemara rejects this approach when it comes vows because language evolves and meanings can change. Another consideration is that the same words can mean something completely different in a different country or culture. Consequently, the Gemara comes to the conclusion "with regard to vows, follow the colloquial language-בִנְדָרִים הַלֵּךְ אַחַר לְשׁוֹן בְּנֵי אָדָם." (Sefaria.org translation)