Single

adjective

1. Having no company solitary
2. Preferring solitude
3. Only, sole
4. Situated by itself isolated

noun

1. One who acts alone and without consultation or the approval of others

noun

1. An ixodid tick (Amblyomma americanum) of the southern, central, and eastern U.S. that attacks mammals and birds, is a vector of several diseases (such as Rocky Mountain spotted fever and ehrlichiosis), and in which the adult female has a single white spot on the back

noun

1. A person who prefers to work, act, or live alone

idiom

1. To do something alone or do something that no one else will do

   "She has had to plough a lone/lonely furrow in her pursuit of reform."