Okay, on the radio

• Word after "Roger" in ham lingo
• Compliant response to a radio message
• "Roger, ___"
• Radio signoff word
• Astronaut's answer
• Cousin to "Roger that"
• Reply on the radio
• Ham radio catchword

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1945, in two-way radio slang, abbreviation and conflation of will comply .

Wiktionary Word definitions in Wiktionary
interj. (context radio communications English) Used to indicate agreement and compliance.