hourglass (n.)

• abbreviation
• astringency
• bottleneck
• cervix
• circumscription
• coarctation
• compaction
• compression
• concentration
• condensation
• consolidation
• constriction
• contraction
• contracture
• curtailment
• decrease
• diminuendo
• isthmus
• knitting
• narrowing
• neck
• reduction
• shortening
• solidification
• strangulation
• striction
• stricture
• systole