Sneakier can be defined as behaving or acting in a secretive or deceitful way. Synonyms for sneakier include sly, cunning, wily, devious, crafty, underhanded, shifty, slippery, and conniving. These words all suggest a lack of honesty or straightforwardness in behavior. A person who is described as sneakier is often someone who is untrustworthy and who manipulates situations to their advantage. It is important to be aware of this type of behavior and to avoid associating with people who display these tendencies. Using these synonyms can help us accurately describe people or situations where we perceive sneakiness being present.