1. (noun) a heavy rain

• cloudburst
• deluge
• downpour
• pelter
• soaker
• torrent

1. (noun) a tornado passing over water and picking up a column of water and mist

• tornado
• twister

2. (noun) a heavy rain

• rain
• rainfall

3. (noun) a channel through which water is discharged (especially one used for drainage from the gutters of a roof)

• conduit

1. (noun) a heavy rain

• deluge
• inundate
• submerge
• deluge
• flood
• inundate
• swamp
• douse
• dowse
• drench
• soak
• sop
• souse
• pelt
• pour
• rain buckets
• rain cats and dogs
• stream
• torrential