Tomcat
/ˈtɑːmkæt/
Definition 1 of 4
Pro Tip 1/3Gender Specific
Use 'tomcat' only for male cats, not females. 
My grandmother's tomcat just had kittens!
Pro Tip 2/3Animal Behavior
'Tomcat' connotes territorial and mating behaviors typical of unneutered males. 
The tomcat marked its territory by spraying.
Pro Tip 3/3Common Misuse
Do not confuse 'tomcat' with 'tom cat', which could mistakenly refer to any male cat. 
She mistakenly called the spayed male 'a tom cat'.