What do 객 (客), 객 (喀), and 객 (䘔) all have in common?

 ANSWER: They are the only 객's in the Korean language.

The Chinese character 客 (객) means "a guest," but it can also mean "extra," superfluous," or "uncalled for." And 喀 (객) and 䘔 (객) both mean "to vomit" or "to spit," though the character 䘔 (객) suggests vomiting "blood" (血 혈).

Here are some interesting Korean words with the character 客 in them:

• 객식구 (客食口) a hanger-on
• 객설 (客說) or 객소리 (客소리) useless or idle talk
• 객귀 (客鬼) the ghost of a man who died while staying abroad
• 객기 (客氣) ill-advised bravery or rashness
• 객년 (客年) last year
• 객담 (客談) idle talk
• 객동 (客冬) last winter
• 객랍 (客臘) last December
• 객비 (客費) "wasteful expenses" or "travel expenses"
• 객사 (客死) to die in a foreign land
• 객수 (客水) "unwanted rain," "unwanted water," or "water drunk at times other than meal times (extra water?)." By the way, in China (水客 수객) can mean "smuggler," "boatman," "fisherman," or "itinerant trader."
• 객수 (客愁) homesickness 
• 객월 (客月) last month
• 객정 (客情) a traveler's lonely feelings
• 객중 (客中) on one's journey, in transit
• 객쩍다 (客쩍다) to be uncalled for, be out of place
• 객추 (客秋) last autumn
• 객춘 (客春) last spring
• 객토 (客토) the soil brought from another place (to improve the soil to which it is brought)
• 객향 (客鄕) a strange land
• 객회 (客懷) homesickness, nostalgia

And here is one Korean word with the character 喀 (객) in it:

• 객혈 (喀血) to spit (cough up) blood, a hemorrhage of the lungs

I did not list all of the Korean words with 객 (客) in them, but I think that is enough to show that the 객 sound in any Korean word comes from either the Chinese characters 客, 喀, or  䘔. And that means, as far as I know, that there are no pure Korean words with the sound 객 in them.

After writing this, I feel a little thirsty, so now I think I will drink some 객수 (客水).