When it comes to finding synonyms for the word "guaranteeable," it's important to think about the context in which the word is being used. Some potential alternatives might include "assured," "certain," "promised," "secure," or "confirmed." Other options might include "reliable," "trustworthy," "dependable," or "predictable." These words all convey a sense of confidence or reassurance, which is often what people are seeking when they say that something is "guaranteeable." Ultimately, the best synonym will depend on the specific situation and the connotations that the speaker or writer is trying to convey.