Final answer:
An informal synonym for fashionable is 'trendy', and is associated with being stylish or in vogue, unlike 'scruffy' which denotes untidiness.
Step-by-step explanation:
An informal synonym for fashionable is trendy, which means stylish or in vogue. The term scruffy, on the other hand, refers to a more disheveled or untidy appearance, which is essentially the opposite of being fashionable or trendy. Throughout different eras, being fashionable has carried various connotations and styles, such as the hipster movement that embraced vintage clothing and the flappers of the 1920s who sought to express independence through new fashions and lifestyles.