The word "stickier" can be replaced with multiple synonyms, including gummiest, tackier, adherent, clingier, and viscid. These words express the ability of substances to stick or adhere to surfaces or objects. In a metaphorical sense, the word "stickier" can also be substituted with synonyms like more difficult or complicated, particularly when referring to a situation or problem that is hard to resolve. It's always good to have a range of synonyms at your disposal while writing essays, articles, or any other form of written communication, as they can help to add variety to your language and make your writing more engaging.