reach

verb

1. stretch out an arm in a specified direction in order to touch or grasp something. "he reached over and turned off his bedside light "Similar: stretch outhold outextend outstretch outstick outreach
   
2. arrive at; get as far as." “Goodbye,” she said as they reached the door

noun

1. an act of reaching out with one's arm."she made a reach for him"
   
2. the extent or range of application, effect, or influence."the diameter and the reach of the spark plug varies from engine to engine"

op·ti·mum

noun

plural noun: optima

1. the most favorable conditions or level for growth, reproduction, or success. "the plant grows within a range of 68 and 78°F, the optimum being 74°"

Origin

mid 19th century: from Latin, neuter (used as a noun) of optimus ‘best’.

Simply put....