lewbʰ-

PIE root meaning to love, care for, or desire.‍​‍​‍​‌​‌​‌​‌​‍​‍​‌​‌​‍​‌​‌​‍​‌​‌​‌​‌​‍​‌​‌​‌​‍​‌​‌​‍​‌​‌​‍​‍​‌ Source of English "love," Latin lubēre, and German lieben.

Discussion

The root *lewbʰ- ("to love, to care for, to desire") is reconstructed in Pokorny (IEW 683–684) and LIV².‍​‍​‍​‌​‌​‌​‌​‍​‍​‌​‌​‍​‌​‌​‍​‌​‌​‌​‌​‍​‌​‌​‌​‍​‌​‌​‍​‌​‌​‍​‍​‌ The root displays regular ablaut (*lewbʰ-/*lowbʰ-/*lubʰ-) and the aspiration of the final labial is confirmed by Germanic and Slavic evidence.

In Germanic, the root is exceptionally productive. Old English lufu ("love") and the verb lufian ("to love") continue the zero grade *lubʰ-, yielding Modern English love. Old High German luba, liubi, and the verb liubēn give Modern German Liebe ("love") and lieben ("to love"). Old Norse has the related adjective ljúfr ("dear, beloved"). Gothic has lubō ("love") and the adjective liufs ("dear"). The English word believe derives from a prefixed form: Old English belȳfan, from *bi-laubjan ("to hold dear, to trust"), showing the semantic extension from love to trust to belief. Lief ("dear, willing") is an archaic survival of the adjective.

Latin lubet, libet ("it pleases") and libīdō ("desire, lust") reflect the zero grade with regular *bʰ > b. English libido is a direct borrowing. The adjective līberālis ("generous, befitting a free person") may be distantly related via the notion of generosity springing from love, though this connection is debated.

In Slavic, Old Church Slavonic ljubъ ("dear") and ljubiti ("to love") preserve the root clearly. Russian ljubov' (любовь, "love") and Polish lubić ("to like") are modern continuations.

The semantic core across branches is consistent: affection, desire, and pleasure, with extensions into trust (English believe) and willingness (English leave in the sense of "permission").

Notes

Source of Latin "lubēre/libēre" (to please), English "love", "lief".