hand in hand

while holding hands, while clutching one another's hand; in close association

Hand in Hand may be:The magazine of Feyenoord supporters club 'Supportersvereniging Feyenoord'Title of the Feyenoord club songHand In Hand, the theme song of the 1988 Summer Olympics Hand In Hand, an anthology of love poems edited by Carol Ann DuffyA song on both the Kingdom Hearts Original Soundtrack and the Kingdom Hearts II Original SoundtrackHand in Hand, a song and single by English dance act Grace (band).Hand in Hand, a 1960 filmA network of public schools in Israel where Jewish and and Arab students grow up in a bicultural environment (www.handinhandk12.org)Hand in Hand, an Indian NGO active in the state of Tamil Nadu, working with child labour elimination, microfinance and job creation, democracy, health, and environmentHand in Hand, a Ugandan soap opera promoting the benefits of vocational training. A batch song in Raffles Institution, a high school in SingaporeHand in Hand, a rap song by DJ Quik, feat. Second to None and El Debarge.Hand in Hand Ministries, Christian charitable organization.
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Adverb
1. together; "hand in hand with hope went fear"; "doctors and nurses work hand in hand to save lives"
2. clasping each other's hands; "they walked hand in hand"

hand in hand, while holding hands, while clutching one another's hand; together, cooperatively

related, together Math and science go hand in hand. They're related subjects.