Abyss

I struggled to find for 15 minutes in the three scanned old English-Japanese-English dictionaries that I have the romajis for ABYSS, DEEP CHASM with little success, I need HUGE as unabridged as possible ROMAJI dictionary quite in the form of my favorite INOUYE's Japanese-English Dictionary. Please name the hugest you know.

In one of them I found SAKEGUCHI, yet tanoshii didn't know it, even worse I can't find the kanjis for it which I need.
Simply, I need all popular and not popular at all romajis for 'abyss'.

Looking up tanoshii for 'abyss':
 

淵	[	淵	]	fuchi		noun
		ふち

Alternate Readings:

 

 

Shintan, likey-likey!
Going to Japanese Wikipedia and looking up 'Mariana Trench' I saw that 'deep sea trench' is written as 海溝.

Also, by chance I found the beautiful cluster housing:

1. serendipity
2. faith
3. sphere
4. crepuscular rays
5. erosion
6. abyss
7. Deep blue

Love it, that's what I need a word both for serendipity and abyss.
They are given under the 収録曲, is that what these three kanjis mean?

In fact I need a word for 'looking far back in the abyss' or 'deep recollection/retrospection'.

Currently my choice is somewhat satellitish, namely 'KAIKO', INOUYE defines it as silkworm/retrospection as tanoshii does:

かいこ	[	かいこ	]	kaiko		noun
		蚕

 

English Meanings:

1. silkworm (Bombyx Mori)

懐古	[	懐	·	古	]	kaiko		noun,	no adjective
		かい	·	こ

 

English Meanings:

1. recalling the old days; nostalgia; reminiscences

回顧	[	回	·	顧	]	kaiko		noun,	suru verb,	no adjective
		かい	·	こ

 

English Meanings:

1. recollection

I like so much this word, combining the silk's made (one pulp reaching 1km in length) with reinvoking.

For so many years, as long as I remember myself, the search for one thing unfolds so many related stuff, it still mesmerizes me.