asociar

To associate — mentally linking two things (asocio ese olor con mi infancia) or formally teaming up or joining as a partner or member (asociarse con un colega, asociarse a un club). The reflexive asociarse specifically covers becoming a partner or member of something, distinct from the plain transitive sense of linking ideas.

• Asocio ese perfume con mi abuela. — I associate that perfume with my grandmother.
• Se asoció con un amigo para montar la tienda. — He partnered with a friend to open the shop.
• Muchos jubilados se asocian a clubes deportivos. — Many retirees join sports clubs.

Dropping the reflexive when the subject itself becomes a member — Spanish needs asociarse a/con, not a bare asociar, for "to join" an organization: me asocié al club, not *asocié al club*.

Often confused with relacionar.