Antonyms for the word "Pertinentness" include irrelevance, inconsequence, triviality, irrelevancy, insignificance, impertinence, and immateriality. These words signify the lack of relevance or importance of something. Pertinentness, on the other hand, means to be relevant, significant, or applicable. It refers to being appropriate, fitting, or related to a particular topic or situation. Using antonyms of "Pertinentness" can lead to confusion, misunderstanding, or irrelevance in communication. Therefore, it is essential to use relevant and appropriate language to ensure effective communication and convey the intended message correctly.