1. Morally binding or necessary
   "it is incumbent on me to attend"

See also: irremissible, obligatory

• speculate
• speculation
• speculative
• speculatively
• speculativeness
• speculator
• speculatory
• speculum
• thane
• thaneship
• thank
• thank offering
• thank you
• thankful
• thankfully
• thankfulness
• thankless
• thankless wretch
• thanks
• thanks a lot
• thanks a million
• thanksgiving
• Thanksgiving cactus
• Thanksgiving Day
• thar