English is rich in near synomyms, mainly as a result of the multiple derivations from Anglo-Saxon (Germanic), Viking, Norman French and, later, deliberate coinages from Classical Latin. This richness can be a source of difficulty for foreign learners. They have to distinguish, for instance, between
shy (German scheu) and timid (Lat timidus)
frail (Norman French import) and fragile (later Latin import)
They also have to cope with a myriad noun-adjective combinations such as
moon - lunar
sheep - mutton
When we, as native speakers of English, are asked the difference between shy v timid, to close v to shut, pale v pallid, etc, we embark on explanations at our peril.
So, to avoid tying yourself in knots, as I did once in front of a class of learners when they asked me to explain the difference between presume and assume, take refuge in a Venn Diagram like the one above. The shaded area is where the area of meaning overlaps, so that either word could be used in a given situation, and the unshaded area is where only one of the words can be used.
And, for the cognoscenti, try Osgood's Semantic Differential, a fun device to while away a cold winter's evening.