This is the verb to obscure with four points of darkness. Dark or false is positioned in the north-west, south-east, north-east and south-west directions. In the Indus noun city, these are the corner points for the city walls. Hence, the ideograph means without barriers. The actual translation will depend upon the context.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-975 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 95: Collections in Pakistan: Suomalainen Tiedeakatemia.
Comment:
In the context of inscription M-975, Mahadevan's sign number 140 might be translated as the adverb thoroughly.
Image Credit:
Indus Script Sign Number 140: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.