The term 'excessively enthusiastic' can be described by the crossword solutions of MANIC (5 letters), GAGA (4 letters), GUSHY (5 letters), and OVEREAGER (9 letters). MANIC is a term used to describe someone who is abnormally and uncontrollably energetic, while GAGA is an informal term for someone who is overly excited or enthusiastic. GUSHY is an adjective used to describe someone who is overly emotional or sentimental, and OVEREAGER is an adjective used to describe someone who is overly eager or enthusiastic. All of these words can be used to describe someone who is excessively enthusiastic.