[Answer] The Latin phrase AD ABSURDUM means:

Step 1 : Introduction to the question "The Latin phrase AD ABSURDUM means:"

...The Latin phrase AD ABSURDUM means 'to the point of absurdity'. The Latin word 'ad' means 'to' and the word 'absurdum' means 'absurdity'. E.g., 'the criminal tiringly repeated his innocence ad absurdum'.