(n.) The quality or state of being clear.

CAT acme aerospace aerosphere air hole air pocket airspace all altitude altitude peak apogee atmospheric visibility automatic control blast-off border line bottom price bound boundary boundary condition boundary line bourn break boundary breakoff point bump burn burnout business index ceiling price ceiling unlimited circumscription clarity clearness climax compass confine conspicuity conspicuousness consumer price index cost-of-living index crosswind crown crystal-clearness cutoff cutoff point deadline definiteness definition delimitation demand curve descent determinant distinctness division line eaves elevation eminence empty space end end of burning evidence evidentness exaltation extreme extremity favorable wind finish flight floor floor price fog front frontier hauteur head wind hedge height heighth high visibility high-pressure area high-water mark highest degree highness hole housetop ignition impact inflation inflationary spiral interface ionosphere jetstream lantern launch lift-off limen limit limitation limiting factor line line of demarcation loftiness low visibility low-pressure area low-water mark lower limit manifestness march mark maximum mete ne plus ultra nth degree obviousness overcast overhead patentness peak penthouse percipi perpendicular distance pinnacle plafond plainness pocket price ceiling price index price level prominence ridgepole rising prices rocket launching roof roof garden roof-deck roofage roofing roofpole rooftop rooftree roughness seeing shingles shoot shot skylight slates soup space start starting line starting point stature stratosphere sublimity substratosphere summit tail wind tallness target date term terminal date terminus the whole threshold tiles time allotment top top price toploftiness trajectory tropopause troposphere trough turbulence upper limit utmost utmost extent uttermost velocity peak visibility visibility unlimited visibility zero