otāra : [m.] descent; access; chance; fault.

A.P. Buddhadatta Mahathera, Concise Pali-English and English-Pali Dictionary [available as digital version from Metta Net, Sri Lanka]

Otāra [fr. otarati, BSk. avatāra. The Sk. avatāra is cen- turies later and means ʻ incarnation ʼ] -- 1. descent to, i. e. approach to, access, fig. chance, opportunityotāraŋ labhati. Only in the Māra myth.He, the tempter, ʻ gets his chance ʼ to tempt the Buddha or the disciples, M i. 334; S i.122; iv.178, 185; DhA iii.121. (avatāraŋ labhati, Divy 144, 145) ot˚ adhigacchati, to find a chance, Sn 446. [Fausböll here translates ʻ defect ʼ. This is fair as exegesis. Every moral or intellectual defect gives the enemy a chance. But otāra does not mean defect]. Ot˚ gavesati to seek an opportunity, DhA iii.21. Otārāpekkha, watching for a chance, S i.122. At one passage, A iii. 67 = 259, it is said that constant association leads to agreement, agreement to trust, and trust to otāra. The Com. has nothing. ʻ Carelessness ʼ would suit the context. o. gavesati to look for an opportunity DhA iii.21, and otāraŋ labhati to get a chance S i.122; iv.178, 185; M i.334; DhA iii.21 (gloss okāra & okāsa); cp. avatāraŋ labhati Divy 144, 145 etc. -- 2. access, fig. inclination to, being at home with, approach, familiarity (cp. otiṇṇa and avacara adj.) A iii.67, 259. -- 3. (influenced by ocarati2 and ociṇṇa) being after something, spying, finding out; hence: fault, blame, defect, flaw Sn 446 (= randha vivara SnA 393); also in phraseotārâpekkha spying faults S i.122 (which may be taken to meaning 1, but meaning 3 is accredited by BSk. avatāraprekṣin Divy 322), Mrs. Rh. D. translates the latter passage by "watching for access".

Pali-English Dictionary, TW Rhys Davids, William Stede,