muss
verb /mʌs/
  /mʌs/
(North American English)Verb Forms
| present simple I / you / we / they muss |  /mʌs/  /mʌs/ | 
| he / she / it musses |  /ˈmʌsɪz/  /ˈmʌsɪz/ | 
| past simple mussed |  /mʌst/  /mʌst/ | 
| past participle mussed |  /mʌst/  /mʌst/ | 
| -ing form mussing |  /ˈmʌsɪŋ/  /ˈmʌsɪŋ/ | 
- muss something (up) to make somebody’s clothes or hair untidy- Hey, don't muss up my hair!
 Oxford Collocations DictionaryMuss is used with these nouns as the object:- hair
 Word Originmid 19th cent. (also as a noun in the sense ‘disturbance or row’): apparently a variant of mess.