Learn Hardcore Turkish: Yastık kılıfı yumuşak, uyumak kolaylaşıyor. - The pillowcase is soft; sleeping becomes easier.

It’s a two-noun compound meaning pillowcase. In Turkish this is a bare (indefinite) noun compound: the first noun is bare, and the second carries the 3rd person possessive suffix.

Morphology: yastık (pillow) + kılıf (cover) + 3sg possessive -ı → yastık kılıfı.
The -ı here is not “the”; it’s part of the compound pattern, not definiteness.

How is yastık kılıfı different from yastığın kılıfı?

yastık kılıfı = pillowcase (as an item/type), a compound noun.
yastığın kılıfı = the pillow’s cover/case (of a specific pillow), a true possessive: yastık + genitive -ın + kılıf + 3sg poss -ı. Use yastığın kılıfı when you mean the cover of a particular pillow; use yastık kılıfı for the general item or when the specific owner isn’t the point.

Why is there no “to be” verb in yastık kılıfı yumuşak?

Turkish often uses a zero copula in the present: adjectives and nouns can serve as predicates without a verb. You can add -dır for formality, emphasis, or general truths: yastık kılıfı yumuşaktır is also correct but more formal/neutral-general.

When would I prefer yumuşaktır over yumuşak?

yumuşaktır: formal writing, definitions, or when stating general truths; can add a matter-of-fact tone.
yumuşak: everyday speech, immediate observations. Both are correct; the difference is register/nuance, not meaning.

What role is uyumak playing in uyumak kolaylaşıyor?

Uyumak is the infinitive/verbal noun (“sleeping/to sleep”) functioning as the subject. Turkish infinitives in -mak/-mek are often used as subjects:

Uyumak kolay. = Sleeping is easy. If it’s an object, you mark it with accusative: Uyumayı seviyorum. = I like sleeping.

Why is kolaylaşıyor in the present continuous (-yor) instead of the aorist (-r)?

kolaylaşıyor = is getting/becoming easier (a change happening now/around now or in this situation).
kolaylaşır = becomes/gets easier (habitual or general tendency). In this sentence, -yor highlights the immediate, situational effect of the soft pillowcase.

Could I say Uyumak kolay instead of Uyumak kolaylaşıyor?

Yes, but it’s a different nuance:

Uyumak kolay. = Sleeping is easy (a simple, static evaluation).
Uyumak kolaylaşıyor. = Sleeping is becoming/getting easier (a change toward ease, cause/effect feel).

What does the -laş- in kolaylaşıyor mean?

-laş- (harmonic -leş-) is an inchoative suffix meaning “become X.”

Morphology: kolay-laş-ıyor → become easy + progressive → is getting easier. Related: the causative -laştır- (-leştir-) means “make X easy”: kolaylaştırmak = to make (something) easy.

If I want to say “makes sleeping easier,” how do I say that?

Use the causative kolaylaştırmak and mark uyumak as an object:

Yastık kılıfı uyumayı kolaylaştırıyor. = The pillowcase makes sleeping easier. You can also nominalize the cause:
Yastık kılıfının yumuşak olması uyumayı kolaylaştırıyor. = The pillowcase’s being soft makes sleeping easier.

Is the comma between the two clauses okay?

Yes in informal style; it reads as two closely linked statements. For explicit cause–effect or more formal style, add a connector or punctuation:

Yastık kılıfı yumuşak; bu yüzden uyumak kolaylaşıyor.
Yastık kılıfı yumuşak olduğu için uyumak kolaylaşıyor.
Uyumak kolaylaşıyor çünkü yastık kılıfı yumuşak.

Can I reverse the order of the clauses?

You can, especially if you add a connector:

Uyumak kolaylaşıyor, çünkü yastık kılıfı yumuşak. (natural) Without a connector, swapping them with just a comma sounds choppier.

How do I express “the/a” here? There are no articles in Turkish, right?

Right—Turkish has no articles. Definiteness/specificity comes from context or other words.

For “the/this,” use demonstratives: Bu yastık kılıfı yumuşak. = This pillowcase is soft.
Plain yastık kılıfı can mean “a pillowcase/the pillowcase” depending on context.

What’s going on with the dotless ı in kılıfı? How is it pronounced?

Turkish has two i’s:

i (dotted) = like English “machine” [i].
ı (dotless) = a back, unrounded vowel [ɯ], somewhat like the vowel in “roses” for some accents, but further back. kılıfı is pronounced roughly [kɯˈlɯfɯ].

Why is yastık not changing to yastığın in the compound?

Because in a bare noun compound (yastık kılıfı), only the second noun takes the possessive. The first noun stays bare. If you use true possession (the pillow’s case), then the first noun is in genitive: yastığın kılıfı.

How do I pluralize or specify multiple pillowcases?

Plural goes on the head (second) noun, before the possessive:

yastık kılıfları = pillowcases. If you mean specific ones, add a demonstrative:
Bu yastık kılıfları çok yumuşak. = These pillowcases are very soft.

How do case endings attach to this compound?

They attach to the head noun after the possessive, often with a buffer -n-:

Accusative: yastık kılıfını (kılıf-ı-nı) yıkadım. = I washed the pillowcase.
Locative: yastık kılıfında leke var. = There’s a stain on the pillowcase.
Ablative: yastık kılıfından memnunum. = I’m pleased with the pillowcase.

Is using ve (and) natural here: Yastık kılıfı yumuşak ve uyumak kolaylaşıyor?

It’s grammatical and natural, but ve is neutral coordination. If you want an explicit cause–effect, prefer bu yüzden, bu nedenle, çünkü, or the clause with olduğu için.

Is uyumak the best verb here, or should I use uykuya dalmak?

uyumak = to sleep (or to fall asleep in some contexts).
uykuya dalmak = to fall asleep (the moment of dropping off). If you mean “falling asleep becomes easier,” say: Uykuya dalmak kolaylaşıyor or Uykuya dalmam kolaylaşıyor (for “my falling asleep”).

How is kolaylaşıyor formed and pronounced?

Morphology: kolay (easy) + -laş- (become) + -ıyor (progressive) → kolaylaşıyor.
Pronunciation: [koːlɑj ɫɑʃɯˈjoɾ] approximately; note the dotless ı [ɯ] in -şı-.