нараспа́шку
adverb
conversational
unbuttoned
пальто́ нараспа́шку
unbuttoned coat
он но́сит шу́бу нараспа́шку
he wears his coat open / unbuttoned
conversational
wide open
used in the following idiomatic expressions
у него́ душа́ нараспа́шку
he wears his heart (up)on his sleeve, he is open-hearted