A new word: vain

vain, adjective, /veɪn/

1 
someone who is vain is too proud of their good looks, abilities, or position. used to show disapproval. 
too proud of your own appearance, abilities, achievements, etc.

Men can be just as vain as women.
She is very vain about her appearance.
He is the vainest man I know.

2 in vain

a) 
without success in spite of your efforts. without success. 
without producing a good or desired result.

Police searched in vain for the missing gunman.
A vain effort to quell the public’s fears only made matters worse.
Volunteers searched the area in the vain hope of finding clues.
We searched in vain for the missing earring. [=we searched for the missing earring but did not find it]
He tried in vain to get the baby to sleep.
Her suffering will not be in vain. [=something good will happen because of her suffering]

b) 
without purpose or without positive results. 
to use (a name, especially the name of God) in a way that does not show proper respect)

Altman swore that his son’s death would not be in vain. 
take somebody’s name in vain (=to talk about someone without showing respect for them. 
How dare you take the Lord’s name in vain (=swear using a word such as ‘God’ or ‘Jesus’)?
He took God’s name in vain.
I thought I heard someone taking my name in vain. [=saying my name]

3 

a vain attempt, hope, or search fails to achieve the result you wanted. 
having no success. not producing a desired result.

vain attempt/effort/bid
The young mother died in a vain attempt to save her drowning son.
They made a vain [=unsuccessful] attempt to escape.

4 vain threat/promise etc

a threat, promise etc that is not worrying because the person cannot do what they say they will.

vainly, adverb, /'veɪnli/
The instructor struggled vainly to open his parachute. 
We tried vainly to get a taxi.
Volunteers vainly searched for clues.