Here is our list of American idioms that start with "W":

Wait-and-see attitude:
A skeptical attitude. An attitude where someone will just wait and see what happens. Example: "The best thing to do is to adopt a wait-and-see attitude."

(To) wait tables:
To work as a waiter/ waitress in a restaurant. Example: "Becky waited tables while she was in college."

(To) wait on someone hand and foot:
To serve someone very well; to do anything someone asks you. Example: "I don't mind making you coffee, but don't expect me to wait on you hand and foot!"

Wanna: Conversational form of "want to". Example: "He doesn't wanna come."

(To) wash one's hands of someone/something:
To end one's association with someone or something. Example: "I washed my hands of Tom. I wanted nothing more to do with him."

Washed-up:
No longer important/ in good form. Example: "Why do you hang out with that washed-up actor?"

(To) waste one's breath:
To talk in vain. To waste one's time talking. Example: "Don't waste your breath. He never listens to what anyone tells him."

Wasted (adj.): Very drunk, high. Example: "We got so wasted last night."

Watch your back!: Be careful; Watch out. *this is often meant as a threat or warning*

Way to go!:
Good job! Congratulations! (*sometimes used sarcastically*)

Wear and tear:
Damage as a result of normal use. Example: "They put a lot of wear and tear on their truck during their long road trip."

(To) wear out one's welcome:
To stay too long (at an event, at someone's house, etc.) Example: "Let's only stay with them for 2 days. I don't want us to wear out our welcome."

Weirdo (n.): Strange person. *fairly negative*

Well-off:
Wealthy. Example: "Her parents are well-off."

Well-to-do (adj.): Wealthy; Rich. Example: "She comes from a well-to-do family."

Wet blanket:
A person who discourages others from having fun.

What makes someone tick:
What motivates someone. Example: "He's such a mysterious guy. I don't quite know what makes him tick."

What's with (someone):
What's wrong with (someone). Example: "What's with you? You've been acting strange all day!"

Wheels (n.pl.): Car.

(A) whole lot:
A lot, too many. Example: "There aren't a whole lot of good restaurants in this neighborhood." = There aren't too many good restaurants in this neighborhood.

(To be) wide awake:
To be completely awake. Example: "P1: Were you sleeping? P2: No, I was wide awake."

(A) wild goose chase:
A futile/hopeless pursuit. Example: "We thought he had given us a good lead, but it ended up being a wild goose chase."

Wimp (n.): Weak, cowardly person. Example: "Call me a wimp again and see what happens."

Wired (adj.): Hyper, (overly) alert. Example: "I'm all wired from the two espressos that I drank."

Wishy-washy (adj.): Lacking in strength or character; not concrete; Example: "He gave me some wishy-washy excuse."

(At one's) wits' end:
If you're "at your wits' end" it means that you've tried everything to fix or solve a problem, or to come up with a solution, and you're almost going crazy from not being able to do this.

(With) no strings attached:
Unconditionally. Example: "He said that he just wanted to help me, no strings attached."

(To) work out for the best:
To work out in the best possible way. Example: "It seems bad now, but things will work out for the best."

Work up the courage (to do something): To build up enough confidence (to do something). Example: "She finally worked up the courage to ask him out."

Wrap (something) up (v.): To finish (something); To bring something to a close. Example: "OK, let's wrap things up for today."