aperture; bore; calibre; caliber
path; lane; small diameter; small radius
course; route; path; process; stages
small calibre; small caliber
impulsive and straightforward; guileless
radius of action; combat radius; sphere of activity; range of activity
grain diameter; particle diameter
distance between two points; distance between opposite supports of arch, bridge; span
large-diameter tree (70 cm or larger); stout tree
semi-major axis (esp. in orbital matters)
particle size; particle diameter
conjugate diameter pair; CDP
aperture ratio (inverse of the f-number); relative aperture
semi-minor axis (esp. in orbital matters)
flat length (of a rubber band)
lymphogranuloma venereum; lymphogranuloma inguinale
core diameter (of a fiber)