Close off is a term that can be used to describe the act of blocking or preventing access to something. INSULATE (8 letters) means to protect from heat, cold, or noise by surrounding with material that reduces or prevents the passage of sound, heat, or cold. ISOLATE (7 letters) means to separate or set apart from others. OBSTRUCT (8 letters) means to block or impede the passage of something. Fencein (7 letters) means to enclose with a fence. SEGREGATE (9 letters) means to separate or ISOLATE from others. All of these terms can be used to describe the act of close off.