suboctave /sub-okˈtiv/

1. The octave below
2. (also suboctave coupler) an organ coupler that gives an octave below

• night letter
• night letters
• nightlife
• nightlifes
• night-light
• night-lights
• night-line
• night-lines
• nightlong
• nightly
• night-man
• nightmare
• nightmares
• nightmarish
• nightmarishly
• nightmarishness
• nightmarishnesses
• nightmary
• night-men
• night-night
• night nurse
• night nurses
• night out
• night outs
• night owl