σπλάγχνον, -ου, τό mostly (in NT always) in pl. σπλάγχνα, -ων, τά,

[in LXX: Pro.12:10 (רַחַם, elsewhere rendered by οἰκτιρμοί, Psa.25:6 40:12 and by ἔλεος, Isa.47:6), Pro.26:22 (בֶּטֶן), Wis.10:5, Sir.30:7, 2Ma.9:5 (6), al. ;]

the inward parts (heart, liver, lungs, etc.; Lat. viscera): Act.1:18. Metaphorical, of the seat of the feelings and of the feelings themselves (in Gk. poets, of anger, anxiety, etc.), the heart, affections (the characteristic LXX and NT reference of the word to feelings of kindness, benevolence and pity, is found in π.; see MM, xxiii; cf. Lft. on Php.1:8): 2Co.6:12 7:15, Phm 7 12 20, 1Jn.3:17; σ. οἰκτιρμοῦ, Col.3:12; σ. καὶ οἰκτιρμοὶ, Php.2:1; σ. ἐλέους θεοῦ; ἡμῶν, Luk.1:78; σ. Χριστοῦ Ἰησοῦ, Php.1:8.†

(AS)

the inward parts; the heart, affections