Lose vs. Loose

Lose and loose are liable to be confused.

Lose is a verb. it means not able to find, not have anymore, not win or to mislay.

• Susan loses her pen at least once a week.
• Our cricket team hasn't lost a game all year.
• Sam is always losing his car keys.
• She always loses one sock.

Loose is an adjective. It means not tight or not fastened.

• My new shoes are loose.
• His pants are loose. 
• He has a loose tooth.
• He was wearing a loose shirt.

Loose can also act like a verb meaning to undo as in loose the knot of the rope or set free as in loose the pack of dogs.

• I always lose my handkerchief (correct) --> a lost handkerchief.
• I always loose my handkerchief (incorrect) --> handkerchief is less tight 

• I like my hair loose and flowing (correct) --> loosened hair.
• I like my hair lose and flowing (incorrect) --> hair loss/ lost hair

• I feel I am going to lose my job (correct) --> not have my job anymore.
• I feel I am going to loose my job (incorrect) --> absurd meaning. How can I set free my job or unfasten it.

Note: Loose and loosen are related but not lose. 
Loosen means to make less tight as in Emily has put on weight and so she has had to loosen her belt.