Wordnet 3.0
NOUN (1)
1.
a pining for a loved one;
The Collaborative International Dictionary of English v.0.48:
Love-sickness \Love"-sick`ness\, n.
The state of being love-sick.
[1913 Webster]
WordNet (r) 3.0 (2006):
lovesickness
n 1: a pining for a loved one