longing (adj.) Look up longing at Dictionary.com
early 15c. (implied in longingly), present-participle adjective from long (v.).
longing (n.) Look up longing at Dictionary.com
"yearning, eager desire, craving," Old English langung "longing, weariness, sadness, dejection," verbal noun from long (v.).
2. Specifically, in pathol., one of the peculiar and often whimsical desires experienced by pregnant women. [Century Dictionary, 1899]