The phrase 'limits to' implies the existence of restrictions or boundaries that constrain or hinder something. There are several synonyms for this expression, including 'constraints,' 'barriers,' 'obstacles,' 'parameters,' 'restraints,' 'confines,' and 'ceilings.' Each of these terms indicates a particular kind of limitation that affects the scope or extent of something. For example, 'constraints' suggests external factors that impede progress or movement, while 'barriers' connotes an impassable obstacle that requires overcoming. On the other hand, 'parameters' implies a set of rules or guidelines that determine acceptable boundaries within which to operate. Overall, each synonym for 'limits to' provides a slightly different nuance of meaning, but all highlight the idea of something that restricts or inhibits.