Indub is not a widely recognized English word. However, it shares similarities with the word "indubitable," meaning unquestionable or certain. Synonyms for indubitable include "undeniable," "irrefutable," "undeniably true," "incontestable," and "inarguable." These words describe something that cannot be argued or questioned due to overwhelming evidence of its truthfulness. Other words that share a similar meaning to indub include "indisputable," "unquestionable," and "certain." All of these words convey a sense of absolute certainty and have a powerful impact when used appropriately in writing or speech.