the quality of being difficult to do; "he assigned a series of problems of increasing hardness"; "the ruggedness of his exams caused half the class to fail"
the property of being rigid and resistant to pressure; not easily scratched; measured on Mohs scale
a constitutional tendency to be gloomy and depressed
characterized by or causing or expressing sadness; "growing more melancholy every hour"; "her melancholic smile"; "we acquainted him with the melancholy truth"
a system of means and activities whereby a social institution functions; "the complex machinery of negotiation"; "the machinery of command labored and brought forth an order"
sculpture suspended in midair whose delicately balanced parts can be set in motion by air currents
a port in southwestern Alabama on Mobile Bay
a river in southwestern Alabama; flows into Mobile Bay
capable of changing quickly from one state or condition to another; "a highly mobile face"
moving or capable of moving readily (especially from place to place); "a mobile missile system"; "the tongue is...the most mobile articulator"
having transportation available
(of groups of people) tending to travel and change settlements frequently; "a restless mobile society"; "the nomadic habits of the Bedouins"; "believed the profession of a peregrine typist would have a happy future"; "wandering tribes"
cartilaginous fishes having horizontally flattened bodies and enlarged winglike pectoral fins with gills on the underside; most swim by moving the pectoral fins
any of the stiff bony rods in the fin of a fish
a branch of an umbel or an umbelliform inflorescence
(mathematics) a straight line extending from a point
emit as rays; "That tower rays a laser beam for miles across the sky"
the number of observations in a given statistical category
the ratio of the number of observations in a statistical category to the total number of observations
the number of occurrences within a given time period; "the frequency of modulation was 40 cycles per second"; "the frequency of his seizures increased as he grew older"