The word 'aakaasha' seems to appear only three times
in YS, III 41:
shrotraakaashayoH sambandhasaMyamaad divyaM shrotram .. 41..
(shrotra + aakaashayoH [-yoH: gen/loc dual] sambandha-saMyamaat; divyam;
shrotram)
...and twice in III 42:
kaayaakaashayoH sambandhasaMyamaallaghutuula-samaapatteshcaakaashagamanam ..
42..
(kaaya + aakaashayoH sambandha-saMyamaat; laghu-tuula-samaapatteH;
ca + aakaasha-gamanam .. 42..)
The verbal root (dhaatu) of 'aa-kaasha' seems to be 'kaash':
kAz cl. 1. A1. %{kAzate} (perf. %{cakAze} , 3. pl. %{-zire}) , to be
visible , appear MBh. &c. ; to shine , be brilliant , have an agreeable
appearance ib.: cl. 4. %{kAzyate} Dha1tup. xxvi , 53: Intens. P. A1.
%{cA4kazIti} , %{cAkazya4te} , to shine brightly S3Br. ii Ka1tyS3r. ; to see
clearly , survey S3Br. xi Pa1n2. 7-3 , 87 Va1rtt. 1 Pat.
>From the root 'aa-kaash', there seems to appear only one verbal
form (in Shatapathabraahmana?):
1 AkAz (ind. p. %{-kAzya}) to view , recognize S3Br. vii.
As a noun 'aakaasha' according to CDSL, can have at least
the following meanings:
2 AkAza m. (Ved.) or (later) n. (ifc. f. %{A}) a free or open space ,
vacuity AitBr. S3Br. MBh. &c. [127,1] ; the ether , sky or atmosphere Naigh.
S3Br. Mn. &c. ; (%{am}) n. (in philos.) the subtle and ethereal fluid (supposed
to fill and pervade the universe and to be the peculiar vehicle of life and of
sound) Veda1ntas. &c. ; Brahma (as identical with ether) L. ; =
%{AkAza-bhASita} below Comm. on S3ak. ; (%{e}) loc. ind. in the air (a stage
direction implying something said by or to a person out of sight) Mr2icch.
S3ak. &c.
Well, "as identical with ether" above reminds us of this
suutra:
aakaashas tallin.gaat
That's from the samanvayaadhikaraNa of BS (I.1.22). Swami Shivananda
translates it like this:
The word Akasa i.e., ether here is Brahman on account of characteristic marks
(of that i.e. Brahman being mentioned).
Now, the word 'prakaasha' appears at least in these suutras of YS:
prakaashakriyaasthitishiilaM bhuutendriyaatmakaM
bhogaapavargaarthaM dRshyam. .. 18..
(prakaasha-kriyaa-sthiti-shiilam; bhuuta+indriya+aatmakam;
bhoga-apavarga-artham; dRshyam. .. 18..
[baahyaabhyantaraviSayaakSepii chaturthaH .. 51..]
tataH kSiiyate prakaasha+aavaraNam .. 52..
chakSuHprakaashaasamprayoge 'ntardhaanam .. 21..
(chakSuH-prakaasha-asamprayoge; antardhaanam.h .. 21..
bahirakalpitaa vRttirmahaavidehaa tataH prakaashaavaraNakSayaH .. 43..
(bahiH; akalpitaa vRttiH; mahaa-videhaa tataH prakaasha+aavaraNa-kSayaH.)
