The Pali and Sanscrit words can mean both 'island' and 'lamp'. The meaning depends on the pronunciation and context.
"Therefore Ananda, you should live as islands unto yourselves, being your own refuge, with no one else as your refuge, with the Dhamma as an island, with the Dhamma as your refuge , with no other refuge." DN 16.2.26
In Skt. it is dvipa 'island'
rather than Sky. dipa 'lamp'
. But we do not really know whether the Buddha pronounced the two words alike or not! In the absence of such knowledge, it is perhaps best not to be too dogmatic about the meaning. In any case, it is just 'oneself' that one has to have as one's 'island' (or lamp), not some 'great self' which the Buddha did not teach. p. 569 note 395 The Long Discourses of the Buddha A translation of the Digha Nikaya by Maurice Walshe.Dīpa
Dīpa1 [Ved. dīpa to Ved. dī, dīpyate; Idg. *dei̯ā to shine (see dibba, deva); cp. Gr. di/alos, dh_los; see also jotati] a lamp
J ii.104 (˚ŋ jāleti to light a l.); DhA ii.49 (id.), 94 (id.)
-- acci the flame of a lamp ThA 154; -- āloka light of a l. J i.266; vi.391; DhA i.359; VvA 51; -- (˚ŋ)kara making light, shining, illuminating Nd2 399 (=pabhaŋ kara Sn 1136; but cp. Dh 236 under dīpa2); Vism 203. -- tittira a decoy partridge (cp. dīpaka˚) J iii.64; -- rukkha lit. lamp -- tree, the stand of a lamp, candlestick DhA iv.120; -- sikhā the flame (lit. crest) of a l. Vism 171; DhA ii.49.Dīpa
Dīpa2 (m. & nt.) [Ved. dvīpa=dvi+ap (*sp.) of āpa water, lit. "double -- watered," between (two) waters] an island
, continent (mahā˚, always as 4); terra firma, solid foundation, resting -- place, shelter, refuge (in this sense freq. combd w. tāṇa lena & saraṇa & expl. in Com. by patiṭṭhā) -- (a) lit. island: S v.219; J iii.187; VvA 19; Mhvs vii.7, 41. -- continent: cattāro mahādīpā S v.343; Vv 2010 (=VvA 104); VvA 19; PvA 74http://dsal.uchicago.edu/cgi-bin/philol ... li.1769870