Well, "dilution" in its purest sense refers to a reduction in earnings per share due to the issuance of shares. So, if 100mm shares are issued by a company to acquire a second company, that could either be dilutive or not depending on how much earnings the acquired company has.
In pinks/pennies, the term dilution simply refers to increasing the O/S -- perhaps because so few have actual earnings to dilute.
Whether shares are issued at or below the market price isn't really a distinction made in the pinks/pennies when using the term dilution -- though the closer to the market price, the more capital flows to the firm, reducing the dilutive impact (properly speaking) of the dilution (O/S increase).