The parts are obvious: far, and ache. The usual English substitute, wanderlust, is a different German word, and it aches less.
German noun, built as the far counterpart of Heimweh, homesickness. Not the same word as Wanderlust.
Where the line breaks
Alignment of Fernweh into 5 lanes. Arrives, thins, and breaks are written in each cell. The same information is in the text alternative below.
DEParts
FernFar
WehAche
DESourceFernweh
FernSource
WehSource
ENEnglishCommon substitutewanderlust
wanderBreaksConnotation
lustBreaksConnotation
Common substitute. The common substitute. Wanderlust is itself a German loan, from wandern, to hike or roam, and Lust, desire. It is not Fernweh.
ENEnglishGloss for this platefarsickness
farArrives
sicknessThinsLexical gap
Gloss for this plate. A calque sometimes offered in prose. It is not an established English word.
FRFrenchGloss for this platemal du lointain
lointainArrives
malThinsLexical gap
Gloss for this plate. A gloss. Mal du pays is Heimweh, and using it here would be the wrong pole. French has no established single noun.
ESSpanishGloss for this platenostalgia de lo lejano
lo lejanoArrives
nostalgiaThinsConnotation
Gloss for this plate. A gloss. Nostalgia leans toward what is past or absent, not specifically toward the far.
JAJapaneseGloss for this plate遠い場所への憧れ
遠い場所Arrives
憧れThinsConnotation
Gloss for this plate. A gloss: a longing toward distant places. Longing, 憧れ, is desire-colored. Weh is pain-colored.
Text alternative
English “wanderlust” (common substitute): breaks: connotation. English “farsickness” (gloss for this plate): thins: lexical gap. French “mal du lointain” (gloss for this plate): thins: lexical gap. Spanish “nostalgia de lo lejano” (gloss for this plate): thins: connotation. Japanese “遠い場所への憧れ” (gloss for this plate): thins: connotation.
FernFar
Distance, the far-off. The opposite pole from Heim, home, in Heimweh.
What happens to “Fern” in each lane
Lane
Form
Status
Break
What happens
English
wander
Breaks
Connotation
Roaming, not the far as a place that hurts. The direction is activity, not distance.
English
far
Arrives
—
The far arrives, in the calque.
French
lointain
Arrives
—
The far-off arrives.
Spanish
lo lejano
Arrives
—
The far arrives.
Japanese
遠い場所
Arrives
—
Distant places. The far arrives.
WehAche
Pain, woe, the -weh of Heimweh. An ache, not an appetite.
What happens to “Weh” in each lane
Lane
Form
Status
Break
What happens
English
lust
Breaks
Connotation
Appetite, desire. Weh is an ache. Wanderlust is a zest for going. Fernweh can be a pain at not being far.
English
sickness
Thins
Lexical gap
Sickness matches Weh only roughly, by the model of homesickness. The whole word is a gloss wearing a noun’s clothes.
French
mal
Thins
Lexical gap
An ache, said with mal. Not a dictionary headword of its own.
Spanish
nostalgia
Thins
Connotation
Nostalgia is a softer and more backward ache than Weh. It will do as a phrase and not as an equivalent.
Japanese
憧れ
Thins
Connotation
A yearning, brighter than an ache. Nearer wanderlust’s desire than Fernweh’s hurt, unless context darkens it.
The joint
Heimweh is homesickness, and English already calqued that one into a living word. Fernweh was built as the other pole: the ache aimed outward. Fern is far. Weh is the hurt. The word is not mysterious. It is transparent, and English happened not to lexicalize it.
What English lexicalized instead is wanderlust, a different German compound, desire to wander. Using it for Fernweh is the break on this plate. One word is a pain at the far. The other is an appetite for the road. They can meet in the same person. They are not synonyms, in German or in English.
The glosses, “farsickness,” mal du lointain, nostalgia de lo lejano, 遠い場所への憧れ, all describe the feeling. They thin where they have to choose between ache and longing, and they remain phrases. That is a lexical gap in the strict sense used on this map: no established word. It is not a ban on talking about wanting to be elsewhere.
Why this break matters to a reader
A reader told they have wanderlust when they have Fernweh has been cheered up against the text. The German word can be melancholy. It is sickness aimed at the horizon, kin to homesickness, not a brochure. Call it by the brochure-word and the sentence changes mood. The parts, once seen, keep the mood honest: far, and ache.