1. Very low in volume
   "the low-toned murmur of the surf"
   - low

See also: soft

• subterminal
• subterranean
• subterraneous
• subtext
• subthalamic nucleus
• subthalamus
• subtile
• subtilin
• subtilise
• subtilize
• subtitle
• subtle
• subtleness
• subtlety
• subtly
• subtonic
• subtopia
• subtotal
• subtract
• subtracter
• subtraction
• subtractive
• subtrahend
• subtreasury
• subtropic