syn- /sin-/, sy- /si-/, syl- /sil-/, sym- /sim-/ or sys- /sis-/

Signifying together, with

• gutterbloods
• gutter board
• gutter broadcasting
• guttered
• guttering
• gutterings
• gutter journalism
• gutter-man
• gutter-men
• gutter-merchant
• gutter pair
• gutter pairs
• gutter press
• gutter presses
• gutter press journalism
• gutters
• guttersnipe
• guttersnipes
• guttier
• guttiest
• Guttiferae
• guttiferous
• gutting
• guttle
• guttled