I have seen in the interchangeable use of कोश/कोष in published books from Maharashtra धर्मकोश/न्यायकोश, but मीमांसाकोष, and this variation is also seen in the Marathi usage of these words.  The popular Marathi poem is written as त्या फुलांच्या गंधकोषी rather than as गंधकोशी.  But you have भारतीय-संस्कृति-कोश, ज्ञानकोश etc. and शब्दकोश/कोष almost with equal frequency.  This variation is facilitated by the fact that while श and ष are distinguished in Marathi writing, they are not distinguished in pronunciation, except by a few ultra-conscious Sanskritists of Pune like the Late Professor Arjunwadkar in my memory.  Here is a good example of this variation on the same page:

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Madhav M. Deshpande

Professor Emeritus, Sanskrit and Linguistics

University of Michigan, Ann Arbor, Michigan, USA

Senior Fellow, Oxford Center for Hindu Studies

[Residence: Campbell, California, USA]

On Mon, May 11, 2020 at 4:15 PM Harry Spier via INDOLOGY <indology@list.indology.info> wrote:

From Monier-Williams 2 names of works ending in  koṣa and  89 names of works ending in kośa (I haven`t listed words that aren`t names of works)., 

amarakoṣa
dharmakoṣa

abhidharmakośa
 uddhārakośa
 ekākṣarakośa
 ekākṣarābhidhānakośa
 kathākośa
 candrakośa
 deśīkośa
 deśīyarājaśekharakośa
 dvaṃdvādikośa
 dvirūpakośa
 dviruktikośa
 dvyarthakośa
 dhanaṃjayakośa
 dharaṇikośa
 dharmakośa
 dhātukośa
 nakṣatrakośa
 nāṭakaratnakośa
 nānārthakośa
 nānārthaśabdakośa
 nāmamālākośa
 nārāyaṇacakravartikośa
 nighaṇṭukośa
 nīlakaṇṭhakośa
 nyāyakośa
 pañcarūpakośa
 padārthakaumudīkośa
 padārthakaumudīsārakośa
 pāṭhyaratnakośa
 pāṇinīyasūtrasārakośa
 prajñākośa
 prabandhakośa
 prākṛtakośa
 prākṛtacchandaḥkośa
 bījakośa
 bṛhadamarakośa
 brahmakośa
 bharatadvirūpakośa
 bhāratamālākośa
 bhāvaprakāśakośa
 bhāvaratnakośa
 maṅkhakośa
 madhukośa
 mantrakośa
 mantraratnakośa
 mantraratnāvalīkośa
 mantroddhārakośa
 mahālakṣmīratnakośa
 mātṛkākośa
 mātṛkābijakośa
 mādhavakośa
yādavakośa
raghunandanakośa
ratnakośa
rabhasakośa
rasaratnakośa
rājavyavahārakośa
rādhākṛṣṇakośa
rāmāśramoddhārakośa
rudrakośa
vararucikośa
vastukośa
vastuvijñānaratnakośa
vāgbhaṭakośa
vikramādityakośa
viśvakośa
vṛttamaṇikośa
vṛddhakośa
vedāntaratnakośa
vratakośa
śabdakośa
śarvakośa
śastrakośa
śivakośa
śuddhatākośa
śṛṅgārakośa
śrīguṇaratnakośa
sakośa
saṃkhyāratnakośa
sādhyakośa
sārasvatakośa
subhāṣitaratnakośa
strīkośa
smṛtiratnakośa
svararatnakośa
 harakośa
 haimakośa 

Harry Spier

On Mon, May 11, 2020 at 6:40 PM Dan Lusthaus via INDOLOGY <indology@list.indology.info> wrote:

Dear Dominik,

Others may provide a more informed account — like you, this is not something I’ve given much thought to — but a quick look at the Digital Corpus of Sanskrit, while still only representing a limited albeit important range of Sanskrit literature, lists nearly 500 instances for kośa, starting with Ṛg Veda (41 occurrences), Atharvaveda (13 occurrences), Chāndogyopaniṣad (3 occurrences), Aṣṭādhyāyī (Aṣṭādhyāyī, 4, 3, 42.0 kośāḍ ḍhañ ||),  Buddhacarita (4 occurrences), Hitopadeśa (10x), not to mention Abhidharmakośa, Amarakośa, and so on, but only 4 instances of koṣa (Nighantuśeṣa 1x, Viṣṇupurāṇa 1x, and Āryāsaptaśatī 2x), the nod would seem to overwhelmingly favor kośa. The term can have a range of meanings aside from encyclopedic compendium or lexicon, so many of those instances may reflect a variety of different meanings.

best,

Dan

On May 11, 2020, at 5:54 PM, Nathan McGovern via INDOLOGY <indology@list.indology.info> wrote:

Dominik, this doesn't really answer your question, but in Thai (which admittedly does often spell Sanskrit words in non-standard ways, especially in pre-modern texts) the spelling โกษ (koṣa), is quite common, perhaps even preferred, especially in the title โกษาธิบดี (koṣādhipati), which was the official in change of the Phra Khlang, or treasury, in Ayutthaya.

Nathan McGovern

University of Wisconsin-Whitewater

On 5/11/2020 4:38 PM, Dominik Wujastyk via INDOLOGY wrote:

I always thought the first, with ś, was correct, and the second was just an orthographic error.  Then I saw "-koṣa" on the title page of Ingalls's Subhāṣitaratnakoṣa.  He must have thought about this.

So which is "right" and why?

Best,

Dominik

PS I haven't even done elementary due diligence on this question, beyond MW.

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