Synonyms for Tower (same or very similar meaning)
WordNet sense 1 (anything tall and relatively thin that approximates the shape of a column or tower):
column, pillar
WordNet sense 2 (a powerful small boat designed to pull or push larger ships):
towboat, tug, tugboat
WordNet sense 3 (appear very large or occupy a commanding position):
hulk, loom, predominate
From the ODE community, based on WordNet
add/edit