To express friendliness using a concrete noun, you would need to describe a specific action or object associated with it:
Actions:
* Smile: A smile is a physical expression of friendliness.
* Handshake: A handshake is a gesture of welcome and friendliness.
* Hug: A hug is a physical expression of affection and friendliness.
* Invitation: An invitation can be a tangible way to express friendliness and willingness to connect.
Objects:
* Gift: A gift can be a token of friendship and appreciation.
* Card: A greeting card can be a physical way to express friendliness.
* Letter: A letter can be a tangible representation of a friendly connection.
Ultimately, the best concrete noun to use will depend on the specific context and what you want to emphasize about friendliness.