1. Going down by steps 
2. (of taxes) gradually decreasing in rate on sums below a certain amount

See also: descending, progressive

• iodinating
• iodination
• iodine
• iodine-125
• iodine-131
• iodise
• iodised
• iodize
• iodized
• iodoamino acid
• iodochlorhydroxyquin
• iodocompound
• iodoform
• iodoprotein
• iodopsin
• iodothyronine
• iodotyrosine
• IOL
• ion
• ion beam
• ion engine
• ion exchange
• ion pump
• ionate
• Ionesco