From response +‎ -less.

• (US) IPA^(key): /ɹɪˈspɑnsləs/, /ɹɪˈspɑnslɪs/
• Rhymes: -ɒnsləs, -ɒnslɪs
• Hyphenation: re‧sponse‧less

responseless (not comparable)

1. Having or producing no response.

• “responseless”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.

• porelessness