1. tower

a structure taller than its diameter; can stand alone or be attached to a larger building

2. column, pillar, tower

anything that approximates the shape of a column or tower

Example Sentences:
'the test tube held a column of white powder'
'a tower of dust rose above the horizon'
'a thin pillar of smoke betrayed their campsite'

• column
• pillar

3. towboat, tower, tug, tugboat

a powerful small boat designed to pull or push larger ships

• towboat
• tug
• tugboat

4. hulk, loom, predominate, tower

appear very large or occupy a commanding position

Example Sentences:
'The huge sculpture predominates over the fountain'
'Large shadows loomed on the canyon wall'

• hulk
• loom
• predominate