"Absorption bands" refer to specific regions in the spectrum of electromagnetic radiation where a substance absorbs or takes in light of certain wavelengths. Full definition
The CO2 climate forcing does not increase as rapidly as the CO2 amount because of partial saturation of CO2 absorption bands [75]. (journals.plos.org)
Also realise that because the CO2 IR absorption bands near the earth's surface are saturated, the phenomenon of self - absorption means incremental CO2 climate sensitivity is probably slightly negative. (judithcurry.com)
If you carefully study the atmospheric absorption bands you will see that oxygen / ozone does show some absorption in the 14 - 15 um range. (wattsupwiththat.com)