Hidden, as motives

• More remote
• Beyond what is openly said
• Intentionally kept concealed, as a motive
• Covert, as a motive
• One kind of motive
• Concealed, as a motive
• Lying beneath what is revealed

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1640s, "on the other side of," from Latin ulterior "more distant, more remote, farther, on the farther side," comparative of *ulter "beyond" (see ultra- ). The sense "not at present in view or consideration" (as in ulterior motives ) is attested from 1735. ...

Wikipedia Word definitions in Wikipedia
For the London-based band, see Ulterior (band)