(a.) Concave on both sides; as, biconcave vertebrae.

Autobahn Cynthian S-shaped US highway achievement alerion alley alleyway animal charge annulet argent armorial bearings armory arms arterial arterial highway arterial street artery artificial satellite autoroute autostrada avenue azure bandeau bar bar sinister baton bearings belt highway bend bend sinister biconcave bicorn billet blazon blazonry blind alley blooming blossoming bordure boulevard broad arrow budding burgeoning bypass byway cadency mark camino real canton carriageway causeway causey chaplet charge chaussee chevron chief circle circumferential circus close coat of arms cockatrice corduroy road corniform coronet county road court crescendoing crescent moon crescent-shaped crescentic crescentiform crescentlike crest cross cross moline crown cul-de-sac dead-end street decrescent decrescent moon demilune developed device difference differencing dike dirt road drive driveway eagle ermine ermines erminites erminois escutcheon expanding expressway falcate falciform falcon fess fess point field file flanch fleur-de-lis florescent flourishing flowering freeway fret full moon full-fledged full-grown fully developed fur fusil garland gibbous moon gravel road griffin growing grown grown-up gules gyron half circle half-moon harvest moon hatchment helmet hemicycle heraldic device highroad highway highways and byways honor point horn-shaped horned horseshoe hypertrophied impalement impaling increasing incremental increscent increscent moon inescutcheon intensifying interstate highway label lane lengthening lion local road lozenge lunar lunate lunette luniform lunula lunular lunule main drag main road mantling marshaling martlet mascle mature menisciform meniscoid meniscus metal mews moon moon-shaped moonlike motorway motto mullet multiplying new moon nombril point octofoil on the increase or orb of night ordinary orle overdeveloped overgrown pale paly parkway pave paved road pean pheon pike place plank road primary highway private road proliferating purpure quadrant quarter quartering queen of heaven queen of night right-of-way ring road road roadbed roadway rose route nationale row royal road sable saltire satellite scutcheon scythe secondary road sector semicircle semicircular semilunar sextant shield sickle sickle-like sickle-shaped sigmoid silvery moon snowballing speedway spread eagle spreading sprouting state highway street subordinary superhighway swelling tenne terrace the wandering Moon thoroughfare thriving