Tennessee Coal, Iron and Railroad Co., acquired by U.S. Steel corporation

Tall Clubs International, the parent organization to many clubs of tall people in North America

Theme-Centered Interaction, a method of psychotherapy by Dr. Ruth Cohn

Tele-Communications Inc., a now-defunct cable television company, acquired by AT&T and then by Comcast

Tricyclic antidepressant medication^[1]

The Children's Investment Fund, a London-based hedge fund.

Thistletown Collegiate Institute, a school in the Toronto District School Board

Turks and Caicos Islands, a British territory consisting of two islands in the Caribbean