the capacity to understand a broad range of topics; "a teacher must have a breadth of knowledge of the subject"; "a man distinguished by the largeness and scope of his views"
a device for showing the operating condition of some system
a signal for attracting attention
(chemistry) a substance that changes color to indicate the presence of some ion or substance; can be used to indicate the completion of a chemical reaction or (in medicine) to test for a particular reaction
an obstruction that stands in the way (and must be removed or surmounted or circumvented)
something immaterial that stands in the way and must be circumvented or surmounted; "lack of imagination is an obstacle to one's advancement"; "the poverty of a district is an obstacle to good education"; "the filibuster was a major obstruction to the success of their plan"