ˈjɛləʊ/

adjective

1. of the colour between green and orange in the spectrum, a primary subtractive colour complementary to blue; coloured like ripe lemons or egg yolks.
"curly yellow hair"

synonyms: yellowish, yellowy, lemon, lemony, 
amber, gold, golden; 

2. informal

not brave; cowardly.
"he'd better get back there quick and prove he's not yellow"

synonyms: cowardly, lily-livered, faint-hearted, chicken-hearted, pigeon-hearted, craven, spiritless, spineless, 
timid, timorous, fearful, trembling, quaking, shrinking, 
cowering, afraid of one's own shadow, pusillanimous, 
weak, feeble, soft; 

noun

1. yellow colour or pigment.
"the craft detonated in a blaze of red and yellow"

2. a yellow ball or piece in a game or sport, especially the yellow ball in snooker.
"he missed an easy yellow in frame four"

verb

1. become yellow, especially with age.
"the cream paint was beginning to yellow"